Question

if引导的宾语从句的用法

Answer 1

whether和if都可以引导宾语从句，表示“是否”，在口语或间接引语中两者可以互换使用。如：
I wonder if / whether I can get some advice from you.
Ask him whether / if he can come.
但在有些情况下，whether和if的用法有一定区别。
1. whether引导的从句常可以与连词or或or not直接连用，而if一般不能。如：
正： Let me know whether you can come or not.
误： Let me know if you can come or not.
2. 当宾语从句提到句首时，只能用whether引导，而不能用if。如：
正： Whether it is true or not, I can’t tell.
误： If it is true or not, I can’t tell.
3. whether可以引导带to的不定式，if则不能。如：
正： I don’t know whether to accept or refuse.
误： I don’t know if to accept or refuse.
4. whether及其引导的成分可放于介词之后，作介词的宾语，但if不能。如：
正： I worry about whether I hurt her feelings.
误： I worry about if I hurt her feelings.
5. whether可以引导从句，作主语、表语或同位语，而if不能。如：
正： It was uncertain whether he would come.
误： It was uncertain if he would come.
正： His first question was whether Tom had arrived yet.
误： His first question was if Tom had arrived yet.

Answer 2

1、主将从现 ：
If it rains(从句) ,I will stay at home（主句）.
=I will stay at home if it rains.

2、一般现在时：
If you drive too fast ,you may have an accident.
=You may have an accident if you drive too fast

3、主句为祈使句,从句要用一般现在时态：
Don't play computer games if you don't finish your homework.

whether和if都可以引导宾语从句，表示“是否”，在口语或间接引语中两者可以互换使用。如：
I wonder if / whether I can get some advice from you.
Ask him whether / if he can come.
但在有些情况下，whether和if的用法有一定区别。
1. whether引导的从句常可以与连词or或or not直接连用，而if一般不能。如：
正： Let me know whether you can come or not.
误： Let me know if you can come or not.
2. 当宾语从句提到句首时，只能用whether引导，而不能用if。如：
正： Whether it is true or not, I can’t tell.
误： If it is true or not, I can’t tell.
3. whether可以引导带to的不定式，if则不能。如：
正： I don’t know whether to accept or refuse.
误： I don’t know if to accept or refuse.
4. whether及其引导的成分可放于介词之后，作介词的宾语，但if不能。如：
正： I worry about whether I hurt her feelings.
误： I worry about if I hurt her feelings.
5. whether可以引导从句，作主语、表语或同位语，而if不能。如：
正： It was uncertain whether he would come.
误： It was uncertain if he would come.
正： His first question was whether Tom had arrived yet.
误： His first question was if Tom had arrived yet.

Answer 3

这是由一般疑问句变来的。引导的从句放在谓语动词后面。
例如： I don't know if he will go there.
老师祝你学习进步！
望采纳，多谢！^_^

Answer 4

引出宾语从句的连词分为“that 、whether 、if 、wh-”
其中if 和whether 引导宾语从句时 ，意为“是否” ，含有不确定性，不在从句中充当成分。
如 I asked her if /whether she heared from Uncle Li .
(我问她是否收到了李叔叔的来信）

祝学习进步

Answer 5

请注意3点
一、if引导宾语从句时，作“是否”讲，常放在动词ask 、see 、say 、know和find out等后面。如：

例1 Nobody knows if it will rain tomorrow. 没有人知道明天是否下雨。

例2 Lucy asked if they had a cotton sweater .露西问他们是否有棉制的羊毛衣。

二、if引导宾语从句时，要注意三个方面，即连词、语序和时态。

1 if不能和that 或其它连词（副词）同时使用，也不能省去。如：

例3 我不知道他今天是否会来。

[误] I don’t know that if he will come here today .

[正] I don’t know if he will come here today .

例4他走过来看看猫是否出了毛病。

[误] He came to see what if there was wrong with his cat .

[正] He came to see if there was wrong with his cat .

2 if引导的宾语从句时，虽具有疑问意义，但从句语序应用陈述句语序。如：

例5 Did you know the way to the hospital ? The old woman asked me .

The old woman asked me .if I knew the way to the hospital .老妇人问我是否知道去医院的路。

3 if引导的宾语从句应和主句的时态保持一致。即主句为一般现在时，从句用任一种时态；主句为一般过去时，从句则用过去时中的任一种时态。如：

例6 I don’t know if he has come here . 我不知道他是否来过这儿。

例7 Tom asked if I had read the book . 汤姆问我是否看过这本书 。