Question

Tom had been studying French hard for nearly three years    he mastered it．

A．a(chǎn)fter

B．when

C．since

D．before

Answer 1

D

試題分析:句意：——湯姆努力學了將近三年后才精通了法語。A在……之后；B當……時；C自從；D在……之前。根據(jù)前后句時態(tài)可知“學習法語”發(fā)生在“掌握法語”之前，所以用before，答案選D。