初级英语语法必刷2000题：11-15

can't=not

not...until

won't+实意动词or be动词

finish doing sth

have enough to do sth

must+主语+v原+其他

否定：no,主 need't(单数)

no,主 dosn't 或don't have to（复数）

may+主+v原+其他？

肯定：yes,you can

否定：no,you can't