pp2-113?

113. (That) brought about the widespread extinction of the dinosaurs is (unknown); it (must), however, (have invloved) major changes in the environment.

A错, 笔记说改为WHAT, 为什么that 不可以引导主语从句呢? 还有一点不明白, 此句中的however到底是连词还是副词? 如果是连词的话是不是要连接一个从句? 还有分号可以连接一个从句和主句吗?

WHAT引导名词性从句作主语

that不可以引导主语从句吗? 我看高分语法中That可以引导主语从句.

eg: That she has gone insane is sheer rumor.

有哪位好心人能详细解答一下? 我过两天就考试了

请比较一下你的例句和上面的题目之间有什么区别。that引导的主语从句中，that不做句中成分，也可以说拿掉that后从句是完整的。可是上面的题目中若拿掉that明显缺少主语。