so many students ( ) because of the bad weather,the exam had to be put off
问题描述：
so many students ( ) because of the bad weather,the exam had to be put off
A were late B been late C has been late D being late
答
D逗号后面没有并列连词and,说明前后两句话不是并列关系.the exam had to be put off是一个句子,有主语（the exam)有谓语（had to be put off),说明这是一个句子.那么逗号前面就不是一个句子,而是一个短语.A、C两项只...being late 求解释这是什么非谓语,, doing 表主动done表被动这个being late算什么。。being late算主动。being是系动词的现在分词形式，late是它带的表语。系动词属于不及物动词，它没有被动。其实现在分词啊，过去时分词啊，不定式啊，这三个都是非谓语动词。非谓语动词就是不能充当谓语的动词。我们知道，本题的主句在逗号后面。其主语是the exam，谓语是had to be put off。一个句子只能有一个谓语，因此逗号前面只能用非谓语动词的形式。如果逗号后面有一个and，那么前后两者就是并列关系的分句了，那么前面就要选A。