He ---- his wallet on the ground 为什么用dropped 而不用fell
问题描述：
He ---- his wallet on the ground 为什么用dropped 而不用fell
答
drop vt.掉落
fall vi.摔倒，常用结构：fall off
答
fall是不及物动词
答
fell是自己落下
而drop可以是有人扔下