There are three kinds of Subordinate Clause:
1. Noun Clause
2. Adverbial Clause
3. Adjective Clause
1. Noun Clause in a sentence does the function of a noun. It functions as
(i) What you say is true.
(ii) I knew that the boy was visually impaired.
(iii) I don’t know whether he will go or stay at home.
(iv) I don’t know about what you plan.
A Noun Clause is generally introduced by that and question words such as why, what, how, etc.
2. Adverbial Clause in a sentence does the function of an adverb.
(i) He got good marks because he was sincere.
(ii) They left the purse where they found it.
(iii) Rohit visits hill stations whenever he has extra money.
(iv) I went to him so that I might help him.
(v) Walk fast lest you should miss the train.
3. Adjective Clause in a sentence does the function of an adjective.
(i) This is the man who gave me money.
(ii) He gave me the book which I wanted.
(iii) This is the car that I bought.
(iv) The man whom you talked is a social activist.
(v) The girl whose ring was lost went to the police station.