Computers ____ in offices and homes since 1970s. 
#100256
A
have been used
B
had been used
C
was used
D
has been used
推荐题目
---- Flight 551 for Dallas ________. I must be off now. ------Have a pleasant trip then.
#102346
A
is being announced
B
has announced
C
was announcing
D
had been announced
Before ___ a loan ____, calculate (核算) your monthly costs.
#100826
A
taking; off
B
taking; away
C
taking; out
D
taking; over