if如果引導(dǎo)賓語從句就翻譯成“是否”,“會(huì)不會(huì)”,用于直接引語的疑問句變?yōu)殚g接引語的陳述句.有時(shí)也是可以用于自己覺得有疑問而連接賓語從句的連詞.在大多數(shù)情況下其實(shí)也等同于whether.而且,主句是什么時(shí)態(tài)從句就是什么時(shí)態(tài).（即過去式就是過去式,現(xiàn)在式就是現(xiàn)在式）
如：She asked Tom if Susan would come here.
【本來是：She asked Tom ,“Will Susan come here?”,將引號(hào)去掉就還原成上述句子了.如果不是疑問句,比如：She told Tom,“Susan will come here.”,則不能用if,應(yīng)該用that引導(dǎo),即：She told Tom（that）Susan would come here.】
如：I'm wondering if the car will break down.
在狀語從句中,if就翻譯成“如果”.
如：If the weather goes bad ,we won't go swimming.
【這句不光是條件狀語從句,也有一個(gè)重點(diǎn),即：主將從現(xiàn).即主句用將來式（有will之類的詞）,從句用現(xiàn)在式.條件狀語從句,顧名思義,就是有是否觀念的,如果是這樣就做,不是這樣就不做.won't就是will not的連寫形式】
上述句子也等同于：We won't go swimming if the weather goes bad.