grope for something
phrasal verb with grope verb uk/ɡrəʊp/ us/ɡroʊp/
搜肠刮肚地想，努力搜寻（尤指恰当的言辞、正确的答案）
to try to think of something, especially the right words, the correct answer, etc.
I'm groping for the right words here. 我正在绞尽脑汁寻找此处合适的措词。