情态动词是动词大家族中的重要一员,虽然数量很少,但在表示情态意义上,有着不可替代的作用。情态动词在表示行为主体或说话者的感情和态度时,无人称和数的变化(have to除外)。它本身具有一定含义,但其意义并不完整,必须与其他动词一起构成谓语,才能表达相 Modal verbs are an important member of the big family of verbs. Although they are few in number, they have an irreplaceable role in expressing modality. When a modal verb expresses the feelings and attitudes of a subject or a speaker, no change is made to the number and number of people (except to have). It has a certain meaning in itself, but its meaning is not complete. It must form a predicate together with other verbs to express the phase.