Adjective clauses are sometimes called relative clauses, because they related to something else in the sentence. The adjective clause modifies a nouns phrase in the sentence. It must have a subject and verb and it will begin with a relative pronoun like who or that.
Example: I know a person who can help you.
The first type of clause is the subject pattern clause:
In the subject pattern, the relative pronoun is the subject of the clause. These pattern clauses can both
subjects and objects of sentences:
The woman who / that spoke to us was very nice. This modifies the subject (the woman) of the sentence.
Do you know the woman who / that spoke to us? This modifies the subject (the woman) of the sentence.