所谓宾语补足语是指对宾语的补充说明与宾语之间有主谓或系表关系。动词不定式作状语时一般情况下谓语动词为不及物动词如:He comes here to ask for help. 动词不定式作宾语补足语时通常用於ask sb to do sth结构,如:Please ask him to be quiet. 动词不定式作宾语时谓语动词一般为及物动词,如:He wants to go