by bus, by bike, by ship, by plane 都是表示方法的，通常用作方法状语。如：
He gets to the market by bike．他骑自行车到市场去。
He couldn’t get the car to start and went by bus. 他因没办法发动车子，所以就乘公共汽车去。
We went by plane, but sent all our furniture by ship. 大家坐飞机去，但家具是用船运的。
请问它们可以用作表语吗？
▲若语义需要，by bus, by bike, by ship, by plane等表示方法的介词短语都可以用作表语。如：
The quickest means of travel is by plane. 旅游的最快方法是乘坐飞机。
The best way is by air; the next best is by train. 最好的办法是乘飞机，第二是乘火车。
▲比较下面的句子也属类似使用方法：
Admission is by invitation only. 凭请帖入场。
Payment is by contribution. 付款使用捐赠的方法。
Entrance to the theatre is by ticket only. 凭票进入剧院。
Admission to this school is by examination. 进入该校须经过考试。
