单项选择题

Most environmental problems exist because adequate measures for preventing them ______ taken in the past.

A．was not
B．were not being
C．were not
D．was no to be
<上一题 目录 下一题>
热门 试题

单项选择题
Ice on the road is a major ______ at this time of the year.
A．terror
B．nuisance
C．hardship
D．hazard
单项选择题
To carry out a company's rules and regulations, administrative personnel must know ______.
A．to be firm
B．being firm
C．what to be firm
D．how to be firm
相关试题