问题补充：
As we all know,, the pollution will get worse and worse.
A. not if carefully dealt with
B. until not carefully dealt with
C. if not carefully dealt with
D. when not carefully dealt with
答案：
A. not if carefully dealt with
B. until not carefully dealt with
(答案→)C. if not carefully dealt with
D. when not carefully dealt with
解析：考查过去分词。本句的主语是the pollution ，和动词deal with构成逻辑上的被动关系，用被动态。而主句中已有谓语，动词短语deal with只能用非谓语形式，根据句意，如果不小心处理的话，故选C。句意：我们都知道，如果不小心处理的话，污染会恶化。
