Keep down吃下東西

①to control the size or number of something and prevent it from increasing
壓縮，控制，限制…的規(guī)模。
②to be able to eat or drink something without vomiting
吃（或喝）下東西（而不吐）。

【例句】
I'm going to sleep, so will you try to keep the noise down?
我要睡覺了，你能不能不要太吵？
 
On the day after her operation she couldn't keep anything down.
手術(shù)的第二天，她吃什么都吐。