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conditional clause

main clause

If I don’t hear from you, | I’ll assume the meeting is still on for tomorrow

morning.

main clause

conditional clause

We can manage | 

if you let us know in time.

If

may also occur in substitute structures:

Are you coming? 

If so, can you get ready quickly?

(with clause-substitute so)

If you want to join us, give me a ring. 

If not, then see you next week.

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Some conditional clauses are used to impose conditions by the speaker/writer on the

listener/reader or on the situation. These include clauses introduced by subordinators

such as as/so long as, only if, on condition that, providing/provided (that):

A: Can I borrow this dictionary?

B: Yeah. So long as you don’t hold on to it.

He was released from prison 

on condition that he went into exile.