infinitive HIn5fIn7I7tIv, $-E7tIv n [C] specialized the form of a verb that usually follows "to" (原形动词)，不定式 In the sentences "I had to go"and "I must go", "go"is an infinitive. 在句子I had to go.和I must go.中，go为不定式。 "Go" is the infinitive form. Go为原形动词。