對…瞭如指掌(或倒背如流);把…背得滾瓜爛熟
know sb / sth backwards
to know sb / sth extremely well
She must know the play backwards by now.她現在對這個劇本肯定是倒背如流。
釋義來自《牛津高階英漢雙解詞典》第 9 版