He nagged me so much for a new bike that eventually I gave in.

gave 是动词 give 的过去式，give 的基本意思是"给予"。 in 在这里是副词，表示"进入某种状态"。 gave in 是一个短语动词，意思是"屈服、让步"，表示在压力或坚持下放弃抵抗或改变立场。