he did nothing but do中but的词性?

he did nothing but do中but的词性? i can do nothing but cry这里的but什么词性 i have got nothing to do but depend on myself.but是什么词性,是只有的意 do nothing but good do nothing but 用法 can do nothing but do He could do nothing but 后面跟原型还是不定式 He could do nothing but ( ) for the bus ( ) I could do nothing but wait有时候看到的是 I could do nothing but wa I can do nothing but he wanted nothing but----there. We did nothing but sit in the chair中 but后为什么接动词原形