Tell them you appreciate what they do..这句里面 what they do 前面是不是省略了什么连词?

Tell them you appreciate what they do..what在这里是缩合关系代词相当于,the thing/things thattell them 后面的整体you appreciate what they do是一个宾语从句（直宾）,然后appreciate后面的what they do是一个...