You cannot be too careful when you drive a car.驾车时候，越小心越好。

The final chapter covers organizational change and development. This subject cannot be over emphasized .

3) .usedn‘t 或did‘t use to 为used to (do) 的否定式。

4)。should 除了“应该”一层意思外，考研大纲还规定要掌握其“竟然”的意思。如：I didn‘t expect that he should have behaved like that. 我无法想象他竟然这样做。

三。情态动词被动关系的主动表达法

1. want， require， worth(形容词)后面接doing也可以表示被动意义。

Your hair wants cutting

The book is worth reading

The floor requires washing.

2.need既可以用need to be done 也可以使用need doing ，两种形式都表达被动的意义

The house needs painting= the house needs to be painted.

The watch needed repairing= the watch needed to be repaired.