to是介词时跟doing,为不定式符号跟do另外还要记住一些词后的to是必须用do还是doing给你列举几个用doing的admittoprefer…tobeusedtoleadtodevoteoneselftoobjecttosticktonogoodnousebefondoflookforwardto这些词用todoaimagreearrangeaskdecidebothercarechoosedemanddesiredeterminehopefailhelplearnlongmanageofferplanpretendrefusetendundertakeexpecthateintend……