A subordinate clause depends on a main clause. At B2 you're expected to weave them in fluently to add reason, contrast, condition and detail.
01
Noun Clauses
Clauses that act as a noun — subject, object or complement.
Noun clauses behave exactly like a noun. They can be the subject of a verb, the object of a verb or preposition, or a complement after 'be'. They are usually introduced by 'that', a wh-word (what, who, where, why, how) or 'whether/if'.
As object of a verb
After verbs of thinking, saying and feeling (think, believe, say, suggest, realise, wonder).
I believe that she will succeed.
He wondered whether the meeting had been cancelled.
Nobody knows what really happened that night.
As subject
Often introduced by 'what', 'whoever' or a 'that'-clause (frequently shifted with 'It is...').
What he said surprised everyone.
It is essential that every applicant submit a portfolio.
Whoever finishes first wins the prize.
After prepositions and adjectives
Use wh-/whether clauses (not 'if') after prepositions; 'that' follows adjectives like glad, sure, aware.
We talked about how the policy could be improved.
I'm not sure whether she received the message.
She was aware that her answer had been incomplete.
B2 watch-outs
After a preposition use 'whether', not 'if'.
Subjunctive 'that'-clauses (suggest, insist, recommend) take the bare infinitive: 'I suggest that he be present.'
Don't use a question word order inside a noun clause: 'I don't know where she lives' (not 'where does she live').
Clauses that add information about a noun — defining or non-defining.
Relative clauses modify a noun. Defining clauses identify which one (no commas); non-defining clauses add extra information (commas, no 'that'). Common pronouns: who, whom, whose, which, that, where, when, why.
Defining (essential information)
Identifies the noun. No commas. 'That' is possible; the pronoun can be omitted when it's the object.
The novel that I was reading on the train belongs to my sister.
The candidate who impressed the panel most has been offered the role.
She lives in a village where everyone knows each other.
Non-defining (extra information)
Adds information; the sentence is complete without it. Commas are required and 'that' is not allowed.
My grandmother, who is 82, still cycles to work.
The new policy, which was announced yesterday, has caused widespread debate.
Berlin, where I lived for three years, has changed dramatically.
Reduced relative clauses
Drop the relative pronoun and 'be', or use a participle, to make writing more concise.
The students selected for the programme will receive a grant.
Anyone wishing to attend should register by Friday.
The book lying on the desk is mine.
B2 watch-outs
Use 'whose' for possession with people, animals and things alike.
After a preposition, prefer 'whom' / 'which': 'the colleague to whom I spoke', 'the report on which we relied'.
Clauses that modify a verb — time, reason, purpose, condition, contrast, result.
Adverbial clauses add information about when, why, how, under what condition, or in spite of what. They begin with subordinating conjunctions and can normally move to the start or end of a sentence.
Time & reason
when, while, as soon as, until, before, after / because, since, as, given that.
As soon as the results were published, the team began celebrating.
She left early because she had a train to catch.
Given that funding is limited, we must prioritise carefully.
Condition & purpose
if, unless, provided that, as long as, in case / so that, in order that.
Provided that you submit on time, your work will be considered.
Take an umbrella in case it rains later.
He spoke slowly so that everyone could follow.
Contrast & result
although, even though, while, whereas / so... that, such... that.
Although the experiment failed, the team learned a great deal.
Whereas the north of the country is mountainous, the south is mostly flat.
The film was so moving that several people were in tears.
B2 watch-outs
Don't use 'will' in a future time/condition clause: 'When she arrives' (not 'will arrive').
'Although' joins clauses; 'despite' takes a noun or -ing: 'despite the rain' / 'despite raining'.
Put a comma after a fronted adverbial clause: 'If you finish early, let me know.'