21. In his twenties, he took part in sports and gained a great deal of __________.

A. ability             B. study          C. experience             D. knowledge

22. If you want to _________ university, you should work hard.

A. attend             B. join            C. take part in            D. join in

23. ___________ returning from abroad, he set about setting up a club for young climbers.

A. Upon             B. At              C. In                D. During