1、賓語從句在復(fù)合句中作賓語.引導(dǎo)賓語從句的連詞that一般可省略.
e.g.I hope (that) everything is all right.
2、介詞之后的賓語從句,不可用which或if連接,要分別用what或 whether.
e.g.I'm interested in whether you've finished the work..
I'm interested in what you've said.
3、whether與if都可以引導(dǎo)賓語從句,常可互換.但下面情況不能互換.
①賓語從句是否定句時,只用if,不用whether.
　　e.g.I wonder if it doesn't rain.
　　②用if 會引起誤解,就要用whether.
　　e.g.Please let me know whether you want to go.（此句如果把whether改成if,容易當(dāng)成條件句理解）
　?、圪e語從句中的whether 與or not直接連用,就不能換成if；不直接連用,可換.
　　e.g.I don't know whether or not the report is true.
　　I don't know whether/ if the report is true or not.
　?、芙樵~后的賓語從句要用whether引導(dǎo).whether 可與不定式連用.whether也可引導(dǎo)主語從句、表語從句、同位語從句,還可引導(dǎo)讓步狀語從句,以上均不能換成if.但引導(dǎo)條件從句時,只能用if,而不能用whether.
　　e.g.It depends on whether we have enough time.
They don't know whether to go there.
Please come to see me if you have time.