有一位英语初学者心血来潮，在自己宿舍的门上写上Knock the door before coming in 这样一句英文。说来也巧，不久他的同学就来拜访他，见到门上醒目的英文顿时忍俊不禁，继而就按主人的吩咐去做了。谁知主人一听到"砰"、"砰"的猛烈敲门声大为恼火，冲到门口一看，敲门的是自己的挚友。经他朋友一解释，他才恍然大悟，马上拿笔在knock之后，加上了介词 at。原来， "knock the door"和"knock at the door" 所表达的意思大相径庭，前者意为 "猛敲门"，而后者表达的才是通常所说的 "敲门" 之义。其实，英语中诸如此类的容易用错的动词为数不少，这里再选一些常见的动词，将其分为两大组，分别讨论它们和介词at 搭配使用时所具有的特殊含义。
(一) catch / catch at
clutch / clutch at
grasp /grasp at
hit / hit at
shoot /shoot at
strike /strike at
先请看例句：
How did you catch the big fish?? 这条大鱼你是怎样抓到的?
He caught at the feather floating in the air, but didn't it.
他想去抓飘浮在空中的羽毛，但没抓到。
A stranger suddenly clutched him by the hand from behind.
一个陌生人突然从后面抓住了他的手。
A drowning man will clutch at a straw. 溺水者连稻草也要抓。
The policeman grasped the thief by the wrist. 警察抓住小偷的手腕。
Don't grasp at the delicate branch，or you may break it.
不要去抓这嫩枝，你会把它折断的。
Raising his fist，the man hit the boy on the forehead.
这人抡起拳头，打在男孩的前额上。
The man hit at the boy with his fist，but it narrowly missed him.
这人挥拳朝男孩打去，但差一点，没打中。
The warden shot the prisoner who was attempting to escape.
看守开枪击毙了企图越狱的囚犯。
The hunter shot at the running deer，but missed it.
猎人朝奔跑的鹿开了一枪，但没打中。
At the moment the warden came in with a whip，so the prisoner thought he was going to strike him. 这时看守提着鞭子进来了，犯人心想看守要抽他了。
The warden struck at the prisoner with his whip,but it didn't fall on his body but on the wall.? 看守举鞭朝犯人打去，但鞭子没打在犯人身上却打在墙上。
通过比较不难看出，当动词catch，clutch和grasp单独使用时意为“抓住”，而catch at，clutch at和grasp at意为“想去抓”，“朝（向）……抓去”，但却没有抓到。换言之， 以表示方向。同样，hit和strike意为“打”，而 hit at 和 strike at 意为"朝……打"，但却没有打中。shoot 和 shoot? at 的区别也很类似，因此，不能说：
The hunter shot the running deer， but he missed it.
因为shot（击中）和missed（没打中）在语义上是矛盾的。
(二) shout to / shout at???? throw to / throw at
动词shout以及throw后面既可跟介词to，又可跟介词at，但含义略有不同，值得初学者注意。试比较：
I shouted to the boy across the river at the top of my voice, but he still couldn't hear me clearly.?? 我朝河对岸的男孩大声呼喊，但他仍旧听不清。
It's bad manners to shout at people.?? 对人大嚷大叫是不礼貌的表现。
Jack threw the ball to me.? 杰克把球掷给我。
Jack threw the ball at me.? 杰克有意用球砸我。
在上述例句中，介词to只表示动作的方向，而介词at不但表示方向，还有“故意”，“不礼貌”等含义。
由此可见，英语中的动词使用比较复杂。仅仅掌握了动词本身的多种意义还不够，还要了解动词单独使用和跟介词搭配使用时的意义区别以及同一动词后跟不同介词时的意义区别.切记不可望文生义，否则就难免犯本文开头所说的那种令人啼笑皆非的错误。
下面请读者从下列各句后括号内选择适当的词填人句中：
1．It's hardly possible for you to ___ the running dog．(catch / catch at)
2．Bob ___ the nail with a hammer，but missed it.?? (hit / hit at)
3. He is such a good hunter that he can even ___ a flying sparrow. (shoot / shoot at)
4．John the ball ___ Bob just in time and Bob made a good shot． (throw...at / throw...to)
5．Don't ___ me! It's more than I can bear.?? ( shout to /shout at)
答案:
1. catch
2. hit at
3. shoot
4. threw...to
5. shout at
