knock
单词辨析：
较正式用词，指迅速或突然地用力一击或敲击，可以是有意的，也可以是无意的。
Who struck the first blow?
谁先动手的?
He struck the boy with his stick.
他用手杖打了那个男孩。
The hammers strike the piano strings and make them vibrate.
音锤敲击钢琴琴弦并使之震动。
The huge clock at the Customs House strikes the hours.
海关大钟报时。
普通用词，指用手或器械连续击打，也指在游戏、竞赛或战争中战胜对手。
The poor child was beaten black and blue.
那可怜的孩子被打得青一块紫一块的。
They were frequently cursed and beaten by the employer.
他们常被雇主打骂。
Jack beat Jobe to win the game.
杰克在游戏中战胜了乔布。
The home team beat the visiting team by a large score.
主队以大比分打败了客队。
普通用词，指有目标地猛击，强调用力击中；引申指在精神、经济等方面予以打击。
The missile hit the carrier.
导弹击中了航空母舰。
The brick hit him in the head.
砖块击中了他的头部。
The economic recession hit the family hard.
经济衰退使这家人遭到重创。
指用拳头或器械猛敲、猛打，强调非常用力。
The attacker knocked her to the ground and kicked her hard.
袭击者把她打倒在地并狠狠地踢她。
Somebody is knocking on the door.
有人在敲门。
I wish you wouldn't knock at the table again.
我希望你不要再敲桌子了。
指用手指等轻叩、轻拍或轻敲，意在引人注意，或表示爱抚等情感。
He tapped me on the back.
他轻轻地拍了拍我的后背。
She tapped the table with her fingers.
她用手指敲打桌子。
He tapped his forehead knowingly.
他会心地拍了拍前额。
指用手掌、拳头或硬物用力敲打，以引起他人的注意或重视。
Please knock before you enter.
进来前请先敲门。
He wondered whether it would be proper to knock at her door.
他不知道敲她的门是否恰当。
I heard him knock his pipe out on the mantelpiece.
我听见他在壁炉架上磕打烟斗。
指用指关节、笔等快速轻敲或急拍，意在引人注意或表示某种情感。
The chairman rapped on the table for order.
主席敲桌子要求听众安静。
Angrily, she rapped on his window.
她生气地敲他的窗户。
He would rap his fingers on the desk when he had difficulty working out a math problem.
他做数学题遇到困难时总是要敲书桌。
相关例句：
There was a light knock at the door.
有人在轻轻地敲门。
Can you knock this nail into the wood?
你能把这钉子敲进木头里去吗？
What they said was a real knock to my self-confidence
他们的话是对我自信心的一次重大打击。
Buckets of roses had been knocked over.
一桶桶的玫瑰被撞翻在地。
The stories of his links with the actress had knocked the fun out of him
有关他与那位女演员有关系的传闻使他很不开心。
Someone had knocked him unconscious.
有人把他打昏了。