An adjective clause functions as an adjective, that is, it gives some information about a noun in a sentence (or a pronoun) ( information which is not an action).
The noun modified here is "knife" and the information about the knife, that is the complete adjective clause is "<span> that his dad gave him.
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<span>It expresses more complete ideas.</span>
Answer:
similes they use like or as to compare something but metaphors compare things but don't use like or as