[英语语法手册]情态动词--can, could
助动词 be的形式变化和动词be。be作为助动词的用法有下列几种: 1)be后跟动词的现在分词 可以构成各种进行时态。如: The driver is cleaning the car.司机在擦车。 Yesterday afternoon we were discussing a new plan.昨天下午我们在讨论一个新的计划。 Women in our country are playing an important part in socialist construction.我...