A valve immediately shuts off the gas when the lid is closed.
当盖子合上时，立刻会有一个阀门切断煤气。
《牛津词典》
2
Take an empty two-liter soda bottle, wash it out, fill it with water, screw the lid on tightly and set it into your toilet tank, as far away from the flapper valve as possible.
拿一个两升的空汽水瓶，洗干净，装满水，旋紧盖子，放进马桶的水箱里，离舌形阀越远越好。
3
A radiator lid functions not only as a lid but also as a valve that moves the radiator coolant from the radiator to the reservoir tank when it is hot (when the pressure is high).