put on a cap意思是：戴帽子；戴上帽子。
put on a cap实际用的时候会把“a”换成人称词，比如“your”、“his”“I”等。
put on a cap读音：英 [pʊt ɒn ə kæp]，美 [pʊt ɑːn ə kæp]。
例句：
1、Why don't you put on your cap?
干吗不戴上帽子？
2、He put on his cap and shoved off for home.
他戴上帽子，回家去了。
3、Rommel put on his cap and got out of the car.
隆美尔戴上帽子，从车子里走了出来。