Ahh I don’t think you need to change anything because pushed is a past tense.
In a work of fiction dialogues and descriptions are the best place to look for supporting details that indicate the theme
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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