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.
The second type is the object clause.
In this adjective clause, the relative
pronoun is the object of the clause. This clause can modify both subjects and objects in the sentence.
The people who we met seemed very kind.
The people that we met seemed very kind.
The students to whom we were speaking seemed very intelligent.
The students that we were speaking seemed very intelligent.
Yesterday, we saw the students to whom we were speaking to.
Yesterday, we saw the students that we were speaking to.