情态动词，常用于否定句、疑问句和条件句。后面加上动词原形。否定式直接加not，疑问句将need提前。You needn't be nervous about the test.（需要）2.实意动词。后面接带to的不定式，否定疑问要加do（助动词）I need to repair my car this Monday.
