Plastic bags won’t be allowed to be used for free in the supermarkets. They can’t _________ easily, which does great harm to our environment.
A.break off
B.break in
C.break down
D.break out
答案:C
考查短语辨析。break off 中断,break in 插嘴,break down 分解,break out 发生,句意:塑料袋不允许在超市免费使用。它们不容易分解,对我们的环境有害。所以选C。