【题目】If we had taken such effective measures much earlier, the river___ soseriously now.
A. is not polluted B. would not be polluted
C. had not been polluted D. would not have been polluted
在线课程【答案】B
【解析】选B 句意：如果我们早采取有力措施，现在河水就不会污染这么严重。主句表示与现在事实相反的虚拟语气，用would加动词原形。