do you think在句中是一个插入语,省略不看的话,句子则简化为what is happiness in this picture?
j句子仍然通顺.所以不用加that.怎么判断DO YOU THINK是WHAT IS HAPPENING的插入语，而不是WHAT DO YOU THIK是主句呢？一般在由what /who/where/why等引导的特殊疑问句中，如果出现do you think /do you suppose/do you know,基本上都属于插入语。