1.情态动词should do sth. 应该做…,could do sth.可以做…,shouldn’t do sth.不应该做…;Why don’t you do…?=Why not do…?为什么不做…?
2.也:too用于肯定句和疑问句末,如She is a girl,too. Are you going there, too?also用于肯定句中,于情态v, 助v, be v之后,实义v之前,如They also stayed at home;either于否定句末,如She can’t fall asleep,either. (either还可以表示两者中的任何一个,如Here are two pens,you can choose either. )