Be sure to practise all four language skills -__,reading,writing _英语解答

Be sure to practise all four language skills -__,reading,writing ,listening and speaking
为什么要用that is 不用they are,this is讲一下做法

人气：174 ℃　时间：2019-08-18 16:35:01

解答

that is是that is to say的简略形式,是一种固定搭配,做插入语,意思是“就是说”.作为独立成分,与主句主语没有主谓关系.