是should to do sth 还是 should do sth?

是should to do sth 还是 should do sth? should to do sth还是should do sth must 后面是加to do sth.还是do sth. 是can to do sth.还是can do sth. it 后面动词是do sth.还是to do sth. 是take action do sth还是to do sth? 是want to do sth and do sth还是want to do sth and to do sth? ( )to do sth是副词还是形容词 是take sth.to do sth.还是take sth.to doing sth. 是mind to do sth还是mind doing sth? worry about 是doing sth还是to do sth 到底是learn to do sth还是learn doing sth 是 stand doing sth.还是stand to do sth 是finish to do sth还是finish doing sth 是offer sb sth还是 offer sb to do sth? 是busy doing sth.还是busy to do sth. 是finish doing sth.还是finish to do sth, why not后面是doing sth还是 to do sth