They tried several times to the problem and in the end they succeeded.A. give upB. work o

问题补充：

They tried several times to the problem, and in the end they succeeded.

A. give up

B. work out

C. look through

D. think of

答案：

A. give up

(答案→)B. work out

C. look through

D. think of

解析：本题的含义应该是他们几次尝试解决这个问题，最后成功了，work out表示解决的意思，与句意较符合，故选B。