You should make it a rule to leave things you can find them again.A. when B. where C. then

问题补充：

You should make it a rule to leave things you can find them again.

A. when

B. where

C. then

D. there

答案：

A. when

(答案→)B. where

C. then

D. there

解析：考察状语从句。状语从句Where you can find them again修饰动词短语leave things。句意：把东西放在你能再次找到的地方。故B正确。