Lesson 8.2 – Main Clauses and Subordinate Clauses -

English Grammar Mastery: From Foundations to Fluency

Sentence Structure and Clauses

Lesson 2: Main Clauses and Subordinate Clauses

Lesson: 2 of 9 | Level: 🟠 Intermediate

1. Lesson Overview

Lesson 1 introduced the fundamental distinction between main clauses and subordinate clauses as part of a broader overview of sentence structure. This lesson examines both clause types in much greater depth — exploring the internal structure of main clauses, the full range of subordinating conjunctions and the relationships they express, the positions that subordinate clauses can occupy within a sentence, and the important distinction between finite and non-finite subordinate clauses.

Understanding the relationship between main and subordinate clauses — how they combine, what positions subordinate clauses occupy, and what logical relationships they express — is the foundation of all the more specific clause work that follows in this module.

Objectives

By the end of this lesson, you will be able to:

Describe the internal structure of a main clause — its obligatory and optional elements
Identify and classify all major types of subordinating conjunction by the relationship they express
Explain the different positions that subordinate clauses can occupy in a sentence
Distinguish between finite and non-finite subordinate clauses
Use subordinating conjunctions accurately and effectively across a range of contexts

2. Core Content

A. The Internal Structure of the Main Clause

Every main clause in English contains at minimum a subject and a finite verb. Beyond these two obligatory elements, the main clause may contain a range of additional elements — objects, complements, adverbials — that extend and specify its meaning.

The five elements of clause structure

Element	Abbreviation	Definition	Example
Subject	S	The person or thing performing or experiencing the action or state	Scientists study the deep ocean.
Verb	V	The action or state expressed by the finite verb	Scientists have discovered new species.
Object	O	The person or thing affected by the action	Scientists study the deep ocean.
Complement	C	A word or phrase that completes the meaning of the subject or object	The findings are extraordinary.
Adverbial	A	A word, phrase, or clause modifying the verb or the whole clause	Scientists work in extreme conditions.

The basic clause patterns

English main clauses follow a small number of fundamental structural patterns:

Pattern	Example
S + V	The glacier retreats.
S + V + O	Scientists study the deep ocean.
S + V + C	The findings are extraordinary.
S + V + A	The team works in the deep ocean.
S + V + O + O	The funding body awarded the team a grant.
S + V + O + C	Scientists consider the findings significant.
S + V + O + A	The team stored the samples at −20°C.

Understanding these patterns — and recognising which pattern a sentence follows — is the basis for understanding how subordinate clauses extend and modify the main clause.

B. Subordinating Conjunctions — The Full System

Subordinating conjunctions introduce adverbial subordinate clauses — clauses that modify the main clause by expressing a relationship of time, cause, condition, concession, purpose, result, manner, or comparison. The choice of subordinating conjunction determines the logical relationship between the main clause and the subordinate clause.

Time relationships

Time subordinating conjunctions express when the action of the main clause occurs in relation to the action of the subordinate clause.

Conjunction	Relationship	Example
when	At the same time as / on the occasion that	When the expedition returned, the team began the analysis.
while	During the same period as	While the surface team monitored the instruments, the divers collected samples.
as	At the same time as (simultaneous)	As the submersible descended, the cameras recorded everything.
before	Prior to	The team recalibrated the instruments before the dive began.
after	Following	After the storm had passed, conditions improved significantly.
since	From a past point to the present	Since the monitoring programme began, scientists have recorded thousands of observations.
until	Up to a point in time	The team continued collecting data until the power system failed.
once	As soon as — after a single event	Once the analysis is complete, the findings will be published.
as soon as	Immediately after	As soon as the equipment was deployed, it began recording data.
whenever	Every time that	Whenever conditions allow, the team conducts additional dives.
by the time	Before a specified future point	By the time the expedition returns, the analysis will have begun.
the moment	Immediately at the point when	The system activated the moment the sensor detected movement.

Cause and reason relationships

Conjunction	Relationship	Example
because	Gives the direct reason	The team returned early because the equipment had failed.
since	Gives a known or accepted reason	Since the data was incomplete, no conclusions could be drawn.
as	Gives a reason — often known background	As the conditions were deteriorating, the team decided to surface.
given that	Takes a fact as a reason	Given that the sample size was small, the results must be interpreted with caution.
now that	Reason based on a new situation	Now that the analysis is complete, the team can begin writing up the findings.
seeing that	Informal reason	Seeing that all the data had been collected, the expedition could return.
in that	Formal — specifies a way in which	The approach is limited in that it relies on a single sampling method.

Condition relationships

Conjunction	Relationship	Example
if	Standard condition	If temperatures continue to rise, coral reefs will not survive.
unless	Negative condition — except if	The expedition will not proceed unless the weather improves significantly.
provided that	Condition — on the condition that	The team may proceed provided that all safety checks have been completed.
providing that	Same as provided that — slightly less formal	The study will be published providing that peer review is successful.
as long as	Condition that must be maintained	New species will continue to be discovered as long as exploration continues.
on condition that	Formal condition	Access to the data was granted on condition that the findings would be shared.
supposing that	Hypothetical condition	Supposing that funding were secured, how long would the survey take?
in case	Precautionary condition	The team took extra batteries in case the power system failed.
whether or not	Condition regardless	The expedition will proceed whether or not the weather improves.

Concession relationships

Conjunction	Relationship	Example
although	Concedes a fact while maintaining a contrasting position	Although the sample size was small, the findings were statistically significant.
though	Less formal equivalent of although	Though conditions were difficult, the team completed the survey.
even though	Stronger concession — despite the fact	Even though funding was limited, the study produced important results.
while	Concession — can also express contrast	While the methodology has limitations, it represents the best available approach.
whereas	Contrast between two situations	Deep-sea ecosystems depend on chemosynthesis, whereas surface ecosystems depend on photosynthesis.
even if	Concession in hypothetical contexts	The expedition will proceed even if conditions are not ideal.
despite the fact that	Formal concession	Despite the fact that the sample was small, the results were consistent.
in spite of the fact that	Formal concession	In spite of the fact that funding was limited, the study was completed.
however	Contrast — used as a conjunctive adverb	The sample size was small; however, the findings were significant.

Purpose relationships

Conjunction	Relationship	Example
so that	Expresses the purpose of an action	Data is archived systematically so that future researchers can access it.
in order that	Formal equivalent of so that	The methodology is documented in full in order that the study can be replicated.
in order to	Purpose — followed by to-infinitive	Scientists deploy autonomous vehicles in order to map the ocean floor.
so as to	Formal purpose — followed by to-infinitive	The team recalibrated the instruments so as to ensure the accuracy of the data.
lest	Formal negative purpose — to avoid	The findings were carefully verified lest any errors had been overlooked.

Result relationships

Conjunction	Relationship	Example
so that	Expresses a result — used with so in main clause	The conditions were so extreme that the equipment failed.
such that	Expresses a result — used with such	The diversity of species was such that the team was overwhelmed by the scale of the discovery.
with the result that	Explicit statement of result	The storm intensified, with the result that the expedition had to return.

Manner and comparison relationships

Conjunction	Relationship	Example
as	Manner — in the way that	The team proceeded as the protocol required.
as if	Manner — as though something were true	The species behaved as if it had never encountered a submersible before.
as though	Same as as if	The data appeared as though it had been corrupted.
the way	Informal manner	The team operated the way the manual described.
in the way that	Formal manner	The species responded in the way that the model had predicted.

C. The Position of Subordinate Clauses

A subordinate clause can occupy three positions in a sentence relative to its main clause — and the choice of position affects emphasis, clarity, and style.

Initial position — subordinate clause before main clause

When a subordinate clause appears before the main clause, it is followed by a comma. This position gives the subordinate clause a degree of prominence — the qualifying or contextual information is established before the main message is delivered.

For example:

Although the sample size was small, the findings were statistically significant. Because the equipment had failed, the team was forced to return to port. When the analysis was complete, the findings were immediately submitted for publication.

Final position — subordinate clause after main clause

When a subordinate clause appears after the main clause, a comma is typically not used — unless the clause is loosely attached or expresses a strong concession.

For example:

The findings were statistically significant although the sample size was small. The team was forced to return to port because the equipment had failed. Scientists will continue to discover new species as long as exploration technologies improve.

Medial position — subordinate clause within main clause

A subordinate clause can also be embedded within the main clause — typically between the subject and the verb, or after the object. Medial subordinate clauses are enclosed in commas.

For example:

The species, which was first observed in 1977, has never been found elsewhere. The team, although exhausted from weeks at sea, continued the analysis.

D. Finite and Non-Finite Subordinate Clauses

Subordinate clauses can be either finite or non-finite.

Finite subordinate clauses

A finite subordinate clause contains a subject and a finite verb — a verb marked for tense and agreeing with its subject. All the examples in this lesson so far have been finite subordinate clauses.

For example:

Although the conditions were difficult, the team completed the survey. (were — finite verb, past tense) When the expedition returns, the analysis will begin. (returns — finite verb, present tense)

Non-finite subordinate clauses

A non-finite subordinate clause contains a non-finite verb form — an infinitive, a present participle (-ing form), or a past participle. Non-finite clauses typically do not have an explicit subject — the subject is understood from the main clause.

For example:

To extend the survey, the team required additional funding. (infinitive — purpose) Collecting samples from twelve sites, the team spent three months at sea. (present participle — manner/time) Damaged by the storm, the instruments needed immediate replacement. (past participle — reason)

Non-finite clauses are examined in full in Lesson 7.

3. Usage in Context

Use because for direct causation — the clearest and most explicit way to express a causal relationship.

The expedition returned early because the primary power system had failed beyond repair. Coral reefs are bleaching at an accelerating rate because ocean temperatures are rising.

Use since and as for causal relationships that involve known or background information — these conjunctions are less direct than because and assume the reader already accepts the reason.

Since the data was incomplete, no firm conclusions could be drawn from the preliminary analysis. As conditions were deteriorating rapidly, the team leader decided to surface immediately.

Use although, though, and even though for concession — acknowledging a fact while maintaining a contrasting position.

Although the sample size was small, the results were consistent with those of larger studies. Even though the expedition faced significant weather-related setbacks, the team managed to complete the full survey.

Use whereas to draw a sharp contrast between two parallel situations.

Deep-sea vent communities depend entirely on chemosynthesis, whereas all surface ecosystems ultimately depend on photosynthesis and solar energy.

Use if for standard conditions and unless for negative conditions — the effect they produce is very different.

If the funding is approved, the expedition will depart in March. (positive condition — it may be approved) The expedition will not proceed unless the safety requirements are fully met. (negative condition — it must be met or the expedition will not happen)

Use provided that and as long as for conditions that must be maintained throughout — they imply a more sustained or ongoing requirement than if.

The team may continue collecting data provided that conditions remain within the safe operating range. New species will continue to be discovered as long as the ocean floor remains a priority for scientific exploration.

Use so that for purpose — not so alone, which expresses result.

Data is archived in full so that future researchers can access it without difficulty. (purpose) The equipment failed, so the team returned to port. (result — so as coordinating conjunction)

Use in order that as a more formal alternative to so that in academic and official writing.

The methodology is documented in full in order that the study may be independently replicated by other research teams.

Use in case for precautionary purpose — describing an action taken to prevent a possible negative outcome.

The team carried emergency supplies in case the primary power system failed during the dive.

Place subordinate clauses in initial position to foreground context, qualification, or condition — and in final position to place the emphasis on the main clause.

Because the sample size was too small, the results were inconclusive. (foregrounding the reason) The results were inconclusive because the sample size was too small. (foregrounding the result)

Use while and whereas carefully — while can express either time or contrast, and the intended meaning must be clear from context.

While the surface team monitored the instruments, the divers collected samples. (time — simultaneous) While the methodology has limitations, it is the best currently available. (contrast — concession)

Use even if for hypothetical concession — acknowledging a possible but uncertain condition while maintaining the main claim.

The expedition will proceed even if conditions are not ideal — the scientific importance of the survey is too great to delay further.

In formal and academic writing, use given that and in that for sophisticated causal and specifying relationships.

Given that the sample was collected from a single site, extrapolation to broader regions must be treated with caution. The study is limited in that it relies on a single sampling method that may not capture the full range of species present.

4. Common Errors and Corrections

Error ❌	Correction ✅	Explanation
The team returned early. Because the equipment failed.	The team returned early because the equipment failed.	Because introduces a subordinate clause — it cannot begin a standalone sentence in formal writing.
Although the findings were significant, but they need further verification.	Although the findings were significant, they need further verification.	Although and but both express contrast — using both together is redundant; remove one.
The team continued the dive despite the conditions were deteriorating.	The team continued the dive despite the fact that the conditions were deteriorating.	Despite is a preposition — it is followed by a noun phrase or the fact that + clause, not directly by a clause.
Scientists study the deep ocean since it contains many species.	Scientists study the deep ocean because it contains many species.	Since for reason implies a known, background fact — here because is more appropriate for a direct reason.
While the data was incomplete but the team published the findings.	While the data was incomplete, the team published the findings.	While for concession already implies contrast — adding but is redundant.
The team worked hard so that they can publish by the deadline.	The team worked hard so that they could publish by the deadline.	In a so that purpose clause with a past main clause, the modal backshifts to could.
Unless the funding is not approved, the expedition will not proceed.	Unless the funding is approved, the expedition will not proceed.	Unless already means if… not — adding not creates a double negative.
The species which it was discovered in 1977 is still studied today.	The species which was discovered in 1977 is still studied today.	The relative pronoun (which) is the subject of the relative clause — a separate subject (it) creates a double subject error.
As soon as the analysis will be complete, the findings will be submitted.	As soon as the analysis is complete, the findings will be submitted.	Will is not used in time clauses — use the simple present in the subordinate clause.
Even though the conditions were difficult, however the team completed the survey.	Even though the conditions were difficult, the team completed the survey.	Even though and however both express contrast — using both is redundant; remove one.

5. Lesson Mastery

After completing this lesson, you should now be able to:

✅ Describe the internal structure of a main clause — its obligatory and optional elements

✅ Identify and classify all major types of subordinating conjunction by the relationship they express

✅ Explain the different positions that subordinate clauses can occupy in a sentence

✅ Distinguish between finite and non-finite subordinate clauses

✅ Use subordinating conjunctions accurately and effectively across a range of contexts