观察下列句子并指出黑体部分的语法作用
1．That he finished writing the composition in such a short time surprised us.
2．It's true that inner beauty is very important, but external beauty shouldn't be completely overlooked.
3．Whether we will go for an outing tomorrow remains unknown.
4．Who will be our monitor hasn't been decided yet.
5．What I say is that my pictures aren't hurting anyone.
6．Whom we must study for is a question of great importance.
7．When we arrive at the destination doesn't matter.
8．How this happened is not clear to anyone.
