为什么这句话是主语从句?怎么看出来啊?it's known to the world that Mark Twain is a great American writer.
问题描述：
为什么这句话是主语从句?怎么看出来啊?
it's known to the world that Mark Twain is a great American writer.
答
(Mark Twain is a great American writer) is (known to the world )
答
it 指代that后面的从句Mark Twain is a great American writer
it在句子中做主语,所以是主语从句.