need. 1.情态动词. 常用于否定句、疑问句和条件句.没有人称和时态的变化,后接动词原形. 否定式直接加not,疑问式将need提前. You needn't be told twice about one single thing. 同一件事没有必要对你说两次. 2.实意动词. 有人称和数的变化,后面接带to的不定式,其否定式、疑问式都要通过助动词do构成. I need to go to Beijing this Sunday to attend a meeting. 上面很详细了.我们老师讲过了.
