1.他本不该在哄骗人们后逃掉的.（ought not to have,get away with）

1.He ought not to have got away with it after he lied to so many people.
2.Are you tired of eating the same food every day?What not come here and have a change
3.In order to keep fit,fat in the diet must be cut down and fibre in it must be increased.
第三句话没有给主语,我还是建议用"我们"作主语来完成句子.In order to keep fit,we must cut down fat in our diet and increase fibre in it.