Having an outdoor meal is always fun but it can also be damaging to the planet if .A. pla

问题补充：

Having an outdoor meal is always fun, but it can also be damaging to the planet if .

A. planned not carefully

B. not planning carefully

C. not planned carefully

D. not to be planned carefully

答案：

A. planned not carefully

B. not planning carefully

(答案→)C. not planned carefully

D. not to be planned carefully

解析：考查省略句。当状语从句的主语和主句的主语一致，且状语从句中有be动词的时候，可以把状语从句的主语和be动词一起省略。本题在if后面省略了it is。句意：出去吃饭也行有有趣。但是如果没有被仔细计划，它也可能回破坏我们的地球。故C正确。