when, while, as的用法区别necessary的用法cease doing/to do的区别even though和even if的用法区别every two与every second的区别a great deal of, a lot of, plenty of的区别advise的用法rather than的用法be to和be going to的区别引导从句时用its与whose的区别awake, wake, awaken, waken用法区别accept和accept of的区别介词for用法大全few, little, a few, a little 的区别regret doing/to do的区别across 的用法write 与write about的区别“Way” 短语讲解because的用法归纳another和the other 的区别