not show where one is; not stand up 隐蔽; 不站立
*Keep down! You mustn't let anybody see you. 蹲下! 一定不要让人看见你. keep sb `down repress or oppress (a people, nation, etc) 压制或镇压（人民、国民等）
*The people have been kept down for years by a brutal regime. 人民多年遭受野蛮制度压迫. keep sth `down
(a) not raise (a part of the body) 不抬起（身体某部分）
*Keep your head down! 不要抬头!
(b) retain sth in the stomach 吞下某物; 不吐出来
*The medicine was so horrid I couldn't keep it down, ie I was sick. 这药这么难吃, 我咽不下去.
(c) cause sth to remain at a low level; not increase sth 使某事物处于低水平; 压抑某事物
*keep down wages, prices, the cost of living, etc 保持低工资、低价格、低生活费等
* Keep your voices down; your mother's trying to get some sleep. 小点声, 你妈妈要睡觉了.
(d) not allow sth to multiply or grow 不使某物滋生或生长
*use chemicals to keep pests down 用化学药品消灭害虫.