John _____ knowledge of radio just by staying around the radio station.

　　A. caught on 　　　B. worked up　　 C. took up　　 D. picked up

The salesman scolded the girl _____ and let her off.

A. caught stealing 　 B. caught to steal

C. catching stealing 　 D. catching stolen

Once _____ at the shop, you will be dismissed immediately.

　 A. caught stealing　　 B. caught to steal　

C. catching stealing　 D. to catch to steal

If _______ in class, you will have to clean the classroom for a week as a punishment.

A. caught sleeping　　　　　　

B. caught to sleep

C. catching sleeping　　　　　

D. to catch to sleep

John _____ knowledge of radio just by staying around the radio station.

　 A. caught on　 B. worked up　 C. took up　 D. picked up