单选题
2.
Most environmental problems exist because adequate measures for preventing them______taken in the past.
A、
was not
B、
were not
C、
were not being
D、
had not been
【正确答案】
B
【答案解析】
本题表示在过去时间里所发生的动作或存在的状态，用一般过去时；主浯measures为复数，因此选B)项。
[避错指导] was not用于第一、三人称单数主语；were not being为过去进行时，had not been为过去完成时，时态与本题不符。
提交答案
关闭