问题补充:
If there aretrees, the air in our city will becleaner.
A. less; more
B. more; more
C. more; much
D. much; more
答案:
A. less; more
B. more; more
(答案→)C. more; much
D. much; more
解析:less是little的比较级,表示更少的;more是much和many的比较级,表示更多的;much是许多,大量意思,修饰不可数名词。句意:如果有更多的树木,我们城市中的空气就会清新的多。结合语境可知前文表示对比,下文much用作副词修饰比较级,故选C。