While every possible means __________ to prevent the river pollution, the river

题干

While every possible means __________ to prevent the river pollution, the river in my hometown has still not been restored to its past beauty.

A．is tried	B．are tried
C．has been tried	D．have been tried

上一题下一题 0.64难度单项选择更新时间:2013-10-21 07:34:49

小学学科试题库

初中学科试题库

高中学科试题库