1.tap用作动词可作“拍打”解,指轻微地、反复地拍打。常常用以引起别人对自己的存在、需要或愿望的注意。tap也可作“窃听”“开发利用”“给…放水”“给…提供消息”解。
2.tap多作及物动词,接名词或代词作宾语。可用于被动结构。

tap down(v.+adv.)
轻轻敲下 beat sth slightly
▲tap sth⇔down
Tap the lid down carefully so as not to break the contents.要把盖子轻轻地敲下去,免得把里面的东西打碎。

tap on(v.+prep.)
轻轻敲击(某表面); 轻击…(某部位) beat surface of sth; hit sb/sth lightly on (a part)
▲tap on sth
Someone is tapping on the door.有人在敲门。
It's no use tapping on the door; we can't hear you in the back room.轻轻敲门没用,我们在后屋听不见。
I tapped on the window to let her know I was waiting for her.我轻敲窗户,让她知道我在等她。
▲tap sb/sth on sth
He tapped me on the shoulder.他拍拍我的肩膀。
All those not dancing were tapping their feet on the floor.那些不跳舞的人都用脚在地板上轻轻地拍打着。
The teacher tapped her fingers on the desk impatiently.老师不耐烦地用手指敲桌子。
A wood pecker tapped a hole in a tree.啄木鸟在树上啄了一个洞。

tap with(v.+prep.)
用…轻轻敲打 beat slightly with sth
▲tap with sth
Tap with the heel of your shoe on the window, and he will let us in.用你的鞋后跟敲窗子,这样他会让我们进去。

用作不及物动词
▲S+～(+A)
This music sets your feet tapping.这音乐能使你的双脚不由自主地跟着打拍子。
用作及物动词
▲S+～+n./pron.
He tapped his forehead knowingly.他会心地拍拍前额。
She tapped a typewriter all morning.她打了一个上午的字。
They prepared to tap the nation's natural mineral wealth.他们准备开发国家的自然矿产资源。
The girls were tapping the rubber.姑娘们正在采橡胶。
The nurse tapped the patient's abdomen.护士给病人放出腹水。
The reporter tapped the spokesman for more information.新闻记者要求发言人提供更多的消息。
◇ 用于be ～ed结构
The secret agent suspects that his phone is being tapped.那个特工人员怀疑他的电话正在被窃听。
We have enormous reserves of oil still waiting to be tapped.我们有巨大的石油储量在等待开发。
▲S+～+n./pron.+to-v
She tapped her girl to let her sleep.她轻轻拍着女儿让她睡觉。
He tapped a stick against the window to let me know he'd arrived.他用手杖轻轻敲窗,要我知道他已到达。

tap, knock, rap
参见knock条。

［同义词］ n.  rap, faucet v.  knock, rap
［词源］  ＜古英语tappa(龙头,塞子) ＜古法语taper拟声词

1.tap用作名词作“塞子,龙头”解,指塞住容器口使内外隔绝的东西,尤指用于控制液体从管子或容器流出来的开关。tap也可作“电话窃听”解。可用作可数可词,也可用作不可数名词。
2.tap还可作“轻叩,轻敲”解,可用作可数名词,也可用作不可数名词。

on tap
随时供应的,现成的 ready for use when needed
He has money on tap.他手头有现钱。
We've got a lot of experts on tap to advise.我们拥有许多专家,可随时指点我们。
At this later hour nobody but a desk clerk would be on tap.时间这么晚,除了服务台值勤员以外没有什么人可供差遣了。
The tavernkeeper had three barrels on tap for the evening's celebration.酒店老板为晚上的庆祝活动准备了三桶酒。
I have my own word processor and printer at home, so that everything I need is on tap.我家有自己的文字处理机和打印机,因此我需要什么就随时可以调用。

He forgot to turn the tap off.他忘了关水龙头。
You left the tap running, and the bathwater is running over! 你忘了关水龙头,洗澡水都流出来了!
There was a persistent sound of running water, although he had turned all the taps off.尽管他已关上了所有的水龙头,但仍有持续不断的流水声。
Telephone taps were played on tape recorders in court.在法庭上用磁带录音机放了从电话中窃听的谈话内容。
She heard a few taps on the window.她听见有人轻轻地敲了几下窗户。
After a few taps the cover came loose.一阵轻拍后,封面变松了。

on tap, on the tap
这两个短语意思不同:on tap的意思是“随时供应的,现成的”; 而on the tap则指“在乞讨”“伸手要东西”。例如:
She was always on the tap, borrowing sugar and milk.她借了糖又借牛奶,老是在伸手要东西。
下面两句意思相同:
He gave a little tap at the door.
He gave a little tap on the door.
他轻轻叩门。