n (1)水龙头，活嘴(any of several types of device for controlling the flow of liquid or gas from a pipe，container，etc)[C]：the gas～煤气开关;hot and cold～s on a basin/a bath 洗脸盆/浴缸上的冷热水龙头;turn the～on/off 打开/关上龙头;fit a～to the beer barrel 给啤酒桶上装一个龙头;Don't leave the～s running. 不要让水龙头开着。～-water 自来水;～-root 植物的主根;

(2)窃听(act or an instance of wire tapping)[C]：put a～on sb's phone 搭线窃听某人的电话谈话;

vt (1)从……放(取)出……(get liquid from(a barrel，etc) by piercing it or opening a tap)[T+n，T+n+adv(off)，T+n+prep(from)]：～a cask of cider/a new keg of beer/the barrel of beer 取一桶苹果酒/新取一小桶啤酒/从桶中取啤酒;～off some cider 拧开桶的龙头取些苹果酒;～cider from a cask 拧开酒桶龙头取苹果酒;

(2)(切割树皮)得到……树液，汲取树液(get liquid from the trunk of (a tree) and collect)[T+n]：～rubber trees 割橡胶树取胶;Sugar maples are～ped when the sap begins to flow. 当槭糖树所含糖液饱满时，人们便割树取其糖液。

(3)开发，利用(start using (a source，supply，etc))[T+n，T+n+prep (for)]：The country (nation) must～new sources of energy/its people's best brains/vast mineral wealth. 国家必须开发新的能源/利用国民最优秀的智力资源/开发大量矿物资源。new ways of～ping the skills of young people 开发青年人技术的新途径;～one's resources 利用自己的资源;～sb for money/a loan向某人要钱/要贷款;

(4)安装窃听装置，在电话线上接线窃听(attach a device to (sb's telephone wires) in order to be able to listen to their telephone conversation)[T+n]：I think/suspect that my phone is being～ped. 我认为/怀疑有人在窃听我的电话。

on tap 1)(指啤酒)装在有龙头桶中的;取自酒桶的：beer on～可随时取用的啤酒; 2)现成的，随用随有的：information/extra personnel on～现成的资料/额外人员;By the way you buy new clothes you'd think we had money on～. 你那样随意买新衣服，你以为我们的钱像水龙头里的水一样(源源不绝)呀。