However, at times this balance in nature is ( ), resulting in a number of possibly unforeseen effects.
A troubled B confused C disturbed D puzzled
上期答案
Criticism and self-criticism is necessary ( ) it helps us to find and correct our mistakes.
A by that B in that C on that D at that
本题大意：批评与自我批评是必要的，因为它可以帮助我们发现并改正错误。
一般that引导的从句不作介词宾语，但besides that , but that , except that , in that除外。