问题补充:
Cars play an important role in modern life, but theyalso cause many problems like air pollution.
A. should
B. can
C. must
D. Will
答案:
A. should
(答案→)B. can
C. must
D. Will
解析:考查情态动词。这里的肯定句表示“有时会,可能会”,用can。注意can与must都能用于肯定句中表示肯定的推测与判断,表示具体情形的推测判断用must,而can表示一般性的叙述,“有时会”。