An adjectival clause will always meet three requirements:
1. it will contain a <u>subject</u> and <u>verb</u>
2. it will begine with a <u>relative pronoun</u> (who, whom, whose, that, or which)
3. it will function as an <u>adjective</u>, answering the questions <em>what kind</em>? <em>how many</em>? or <em>which one</em>?
hope this helps (: