新定义英语第二册第6课中开始讲到短语动词的使用方法，也就是大家平时所说的动词短语的使用方法。整个第二册中有关动词短语的使用方法，大多是指同一个动词跟不一样的介词或副词搭配用后，意义发生变化。这种动词短语是各类英语考试中有关词语测试常考的内容，平时应该注意积累区别。智学网为你提供以下有关内容：

knock at

该短语表示“敲”。有时，knock也会用作名词，表示“敲击”，后面也是紧跟介词at。如：

He wondered whether it would be proper to knock at her door.

I was preparing for bed when I heard a knock at the door.

knock...off

该短语表示“把...撞倒”，off后面一般接地址。但knock后面也可以接比率或数字，表示“降低”，此时的比率或数字也可以放到off后面。如：

I knocked the vase off the table and broke it.

The shop assistant knocked 10% off the bill.

It cosplayt me 10 but Ill knock off 20% as its no longer new.

knock off

与knock...off不一样的是，knock off中间一般不插入其他成分，表示“做完某事;下班”。如：

We knock off at 12:30 for lunch.

I can knock off a poem in five minutes.

knock over

该短语表示“撞倒;消除”，应该注意的是：宾语是名词的话，可以放在knock和over中间，也可以放到over后面;宾语是代词的话，则只能放在中间。如：

Dont knock over the bowl of water.

=Dont knock it over.

The students knocked over every difficulty.

=The students knocked it over.

knock out

该短语表示“击倒;打昏”。应该注意的是：宾语是名词的话，可以放在knock和over中间，也可以放到over后面;宾语是代词的话，则只能放在中间。如：

The enemy charged up the mountain, attempting to knock out our forces.

In the fight, the thief knocked the policeman out.

除去以上教程中出现的短语以外，下面这类有关knock的短语也较为常用：

knock down

该短语表示“击倒;撞倒;拆除”。如：

The policemen had to knock down the door to get in.

Knock down the machine before shipping.

knock up

该短语表示“匆忙做完;使...精疲力尽”。如：

Can you knock up a meal for us now?

I was completely knocked up from overwork.

knock it off

该短语常常用作提示语，表示“不要再讲下去”。如：

Knock it off, will you? I cant make a phone call with all this noise going on.

Will you kids knock it off? I cant study.