问题补充:
-----They used to be good friends, but now they are like strangers. ----- How this ?
A. were; come about
B. did; come about
C. were; taken place
D. were; happened
答案:
A. were; come about
(答案→)B. did; come about
C. were; taken place
D. were; happened
解析: come about, take place, happen都是发生的意思,均无被动语态。