The clause that contains a subject and a predicate of its own and does the work of an adverb is called an adverb clause.
Adverb clauses are of many kinds. Of them the following are important.
(a) Adverb Clause of Time,
(b) Adverb Clause of Place,
(c) Adverb Clause of Reason.
(d) Adverb Clause of Manner.
(e) Adverb Clause of Condition.
(f) Adverb Clause of Degree/Comparison.
(g) Adverb Clause of Results/Consequence,
(h) Adverb Clause of Purpose,
(i) Adverb Clause of Concession.
(a) Adverb Clauses of Time:
Adverb Clauses of Time starts with conjunctions of time such as, as soon as, before, after, hardly, when, no sooner, than, since, the sooner, till, until, when, while, scarcely, etc.
Adverb clause of time refers to the time of completion of work of the main clause.
Examples: I met Ahsan when I was at school.
As soon as he came, she left the place.
(b) Adverb clause of place:
It starts with the following conjunctions of place: where, where ever, when, etc.
It refers to the place of the completion of the work of the principal clause. Example: I shall go where he lives
(c) Adverb clause of Manner:
Adverb clause of manner starts with the conjunctions of manner like, as, like, how, however, etc. This clause always sits after the principal clause.
Example: You cannot do the work as your father does.
Principal clause = you cannot do the work
Adverb clause = like your father does
(d) Adverb clause of condition:
This clause indicates condition and starts with the conjunction of a condition like if, whether, unless, but, for, otherwise, provided, suppose, even, etc.
If you want, I will help you.
Unless you walk fast, you will not be able to get the train.
Adverb clause of reasons
This type of clause indicates the reason for completion or not completion of any work. This clause starts with conjunctions of reason like as, since, for, because, that. Example:
He dislikes him because he is lazy.
(e) Adverb clause of degree/comparison.
This clause compares between two things.
This clause starts with than, as —— as, so ———— as, the same — as, etc. This clause sits just after the principal clause.
Examples: Rana is taller than Rumi. (is) He is not as clever as we think.
(f) Adverb clause of consequence.
This clause expresses the result of the principal clause. This clause generally starts with that and modifies the adverb. So/much is used in the main clause.
Examples: He is so weak that he cannot carry the load.
The man is so poor that he cannot buy a good shirt.
(g) Adverb clause of purpose
This clause refers to the purpose of work of the principal clause. This clause starts with subordinating conjunction that, so that, in order that, lest, etc.
Examples: He works hard so that he can shine in life.
I walked fast lest I might miss the train.
(h) Adverb clause of concession
This close expresses the opposite meaning of the statement of the principal clause. This clause starts with though, although, even, even if. Sometimes it starts with whoever, whatever, whichever, however, etc.
Though he is poor he is large-hearted.
I know the time when he will come.