Manhattan SC中的疑问：if VS whether GMAT rules

tintinc

Manhattan SC
Chapter 9 Idioms Strategy
P171

Whether的用法
I do not know whether I will go. 正确。
I do no know whether or not I will go. Suspect
I do not know if I will go. 错误（Manhattan解释为：IF requires a consequence）

请问1) 第三句这个a consequence如何理解？2) GMAT中if这样的用法都是绝对错误的吗？

powers

如果和whether同时出现立刻排除

tintinc

可是这里归为绝对错误的用法。和高中学的语法不一样唉。。。求解释

tintinc

Use if for a conditional idea, whether for an alternative or possibility. Thus, Let me know if you'll be coming means that I want to hear from you only if you're coming. But Let me know whether you'll be coming means that I want to hear from you about your plans one way or the other" (Garner, The Oxford Dictionary of American Usage and Style).

可否这样理解，
if: 你来的话告诉我一声
whether: 你告诉我你会不会来

这样就推出I don't know if I will go. 在逻辑上是不通的？

shallbytwo

在gmat中，
1。if 只做如果
2。不用whether or not， wordy。只用whether。

zyq19911205

whether or not貌似有时候也是正确的，og verbal分册逻辑第10题   At a recent conference on environmental threats to the North Sea, most participating countries favored uniform controls on the quality of effluents, whether or not specific environmental damage could be attributed to a particular source of effluent.

prep 08笔记是这么解释的
1) 在引导宾从的时候只能够用whether，而不能加or not，否则累赘
2) 在引导状从的时候必须加上or not，即whether or not.

牛掰

这个题貌似没有讨论出结果啊！prep08……可能有的时候看manhattan笔记更直观点吧。总结如下：

1.在GMAT中，”if“不可以表示”是否“，只能引导条件状语从句，因为manhattan 说：I do not know if will go，this sentence is wrong cause "if " needs a result!

2.whether 在表示”是否“的时候，到底可不可以加 or not，这个问题待定，不能说绝对错或者绝对对！

这是鄙人的一点拙见，如果发现有漏洞，请各位看官不吝赐教~

seeingyou

摘自Manhattan：
Whether/If
Whether is used when there are alternative choices.
Correct: I don’t know whether I will take the GMAT this month (or not).
Incorrect: Her client didn't tell her if he had sent his payment yet.
Correct: Her client didn't tell her whether he had sent his payment yet.
If is used in a conditional sense.
Ex: If you prepare well you will get a good score.

小桃仁cherry

同意7#的观点，if只用来表示如果怎么怎么样，后面必须跟结果。