7. I ______ have worried before I came to the new school, for my classmates here are very friendly to me.
A
mightn’t
B
mustn’t
C
needn’t
D
couldn’t
needn’t have done本不必做某事，故选项C符合选项。
根据下文for my classmates here are very friendly to me这里的同学对我都很友好，所以是本不需要担心的。
常见情态动词记忆不准致错。