1.是否定句之后通常用 or代替 and.如：He spoke loudly and clearly.他說(shuō)話聲間宏這且清晰.He didn’t speak loudly or clearly.他說(shuō)話聲音不大且不清晰.2.祈使句＋and =if,而祈使句＋or = unless.如：Work hard,and you will succeed.(=If you work hard,you’ll succeed.) 努力工作,你就會(huì)成功.Work hard,or you won’t succeed.(＝Unless you work hard,you won’t succeed.) 努力工作,否則你就不會(huì)成功 3.有時(shí) and與 or可換,如：life and (或or) death (在死)；有時(shí)and no與or互換.如：He has no brothers and no sisters = He has no brothers or sisters.他沒(méi)有兄弟姐妹.4.在選擇疑問(wèn)句中,用or 不用and.如：Is it a pen or a pencil?那是鋼笑還是鉛筆?Which is bigger,the sun or the earth?太陽(yáng)和地球哪個(gè)大?5.在both 之后用and,在either之后用or.如：Both you and he are right.你和他都是對(duì)的.Either you or he is right.不是你對(duì)就是他對(duì).