题目内容：

（）the earth truns around the sun is known to us all.A.that B.what C.which D.the fact

优质解答

选A.这是that引导主语从句,it 作形式主语,that 不能省略.例如：That she is a rich woman is known to us all.众所周知,她是个富有的女人.这句话可以改为用it 作形式主语的句型：It is known to us all that she is ...