[例4]— I usually go there by train.
— Why not______by boat for a change？
A.to try going　B.trying to go　C.to try and go　D.try going
【解析】答案D。why not 后面接不带to 的不定式，因此选D。
[例5]Paul doesn’t have to be made______.He always works hard.
A.learn　B.to learn　C.learned　D.learning
【解析】答案B。make后接不带to 的动词不定式，当其用于被动时，to 不可省略。相同用法的动词还有let，have，see等。
[例6]Tell him______the window.
A.to shut not　B.not to shut　C.to not shut　D.not shut