Do you know that China is one of the most ancient and civilised countries?疑问句怎么能用that引导呢为什么不可以?that 引导宾语成分，这里是宾语从句。比如说 Do you know that he died?是if吧。。if表示如果，亲，我没有蒙你啦，我是英语专业的，专八都拿了，对这个问题是很清楚的。