后面只接不定式的动词。如 :hope,wish,help,decide,ask,learn,teach,choose,agree,plan,encourage,tell,use,invite,send,fail,refuse,offer,afford,preptend,promise,以及词组would like,get/be ready,do/try one’s best,make up one’s mind等。注:help后接不定式时,to可有可无。