flex one's muscles

give a show of strength or power

显示实力

not move a muscle

be completely motionless

一动不动，纹丝不动

muscle in/into

(informal)force one's way into (something), typically in order to gain an advantage

(非正式)（为获取利益）强行挤入（或插手）

he was determined to &B{muscle in on} the union's affairs.

他决意强行插手工会事务。

muscle up

(US informal)build up one's muscles

(美，非正式)使肌肉发达