fill in
—phrasal verbwithfillverbuk/fɪl/us/fɪl/
to do someone else'sworkfor them because they cannot or will not do it themselves
代替；临时补缺
She willfillinforhim while he's at theconference.她会在他开会时代理他的工作。
I'm not herregularsecretary- I'm justfillingin.我不是她的常任秘书，我现在只是临时顶替。