Not until one of his works was published_________to gain his confidence in writing. [ ]

A. he was able      

B. was he able        

C. he had been able  

D. had he been able

排球比赛的场地长18米宽8米，网子两边各一条3米线，国际成年组男子网高2.43米，女子网高（）。

A.2.1米

B.2.18米

C.2.24米

D.2.31米