Gerunds and to-infintives

want, decide, ask, tell,afford, agree, arrange, ask, decide, expect, fail, hope, intend, learn, manage, offer, plan, promise, refuse, wish 等之後用to-infintives
eg.i want to go with you.
they have decided to come.
he told me to wait for him.

finish, admit, avoid, practise,help, stand, consider, delay, dislike, enjoy, feel like, imagine, involve, keep/keep on, mind, miss, postpone, practise, risk, suggest 等之後用gerunds
eg,have you finished packing?
don't delay answering the letter.
how can we avoid catching a cold?