Computers in offices and homes since 1970s.
A. have been used
B. had been used
C. was used
D. has been used
网友回答
(答案→)A. have been used
B. had been used
C. was used
D. has been used
解析：
试题分析:考查动词时态语态。根据since the1970s可以判断句子用现在完成时，再根据主谓一致的原则可知A选项正确。句意：自从二十世纪七十年代以来，电脑被应用于了家庭和办公室。