1.worth doing sth是固定用法.还可以写成worthy to do sth.2.make sence行得通,有意义. I'm trying to open it without tool but it doesn't make sence.我企图徒手打开它但行不通.3.特殊疑问句后面直接跟动词的时候就是特殊疑问词加动词提问.反之亦然.例如:1)Who is the guy's father?谁是那个人的父亲?这里后面跟着所属而非动词.2)Who stole my purse?谁偷了我的钱包? Who did it?这是谁干的?