题干
The manager came over and asked the customer how ___________.
A：did the quarrel come about
B：does the quarrel come about
C：the quarrel has come about
D：the quarrel had come about
答案(点此获取答案解析）
D
投入0.2亿元解决了污染问题，此时社会收益为1.0亿元。这一过程表明：