to do sth.是动词不定式吗?答:hope,mean,long,learn,seek,intend,tend,manage,prepare,remember,forget,plan 加ing start/begin/keep/feel like /practice/like/allowed/pay attention to /be used to/consider +doing sth.(所有介词后面都加doing sth.)see/hear/find/watch sb.doing sth keep/prevent/stop+from doing sth ...