I found some contradictions in SC resources

Question

Hi , please clarify some of these contradictions I have found in SC resources

1.According to GMATclub Grammer book , we can use :  so ..as  in comparision

Mary is not so tall as her sister. p 74
However, Magoosh idiom book : this is always wrong in comparision .

2.Accordng to Aristotle SC : 
 So as to 
 
is used to denote cause and effect. Cannot be used to
replace "in order to"
Correct: John’s grades are so poor as to lead to his expulsion
from the school.

but in Magoosh : so as to is used to replace : so that (clauses of purpose)
correct examples :
1)I went into town so that I could see Marcia before she left.
2) I went into town so as to see Marcia before she left.

3. between  :
Aristotle : between X AND Y 
NOT : between X or Y
(between' and 'among' will ALWAYS take and not or )

Gmatclub book : Johnny had to decide between going to Europe, buying a new car,  or  staying in college. p51

4. Aristotle : " when " will always refer to a specific time period.
Incorrect: When the price goes up, the demand falls down.
However, I have seen many times in more that one resource that when is used as "by the time" , so the above sentence should be right !

foryearss · Answer

I would like to know definitely what are the correct uses of these 4 issues . 
Thanks

ccooley · Answer

I'm not absolutely 100% sure about this, but I believe that the sentence you gave is incorrect. If anybody else can find a citation from an official problem that goes one way or the other, I'd appreciate it.

Correct sentences:

Mary is so tall  that  she hits her head on the ceiling fan.

Mary is not  as  tall as her sister.

There are two SC problems that use this idiom in the most recent Official Guide. One of the explanations states that 'so as to' can mean basically the same thing as 'in order to'. The other explanation doesn't mention the idiom at all one way or the other. Neither one specifically says that this idiom is wrong. If I saw this in a problem, I would look for other grammar or meaning issues.

The Official Guide itself states that "between X OR Y" is incorrect, and "between X AND Y" is correct. It's on page 675 of the 2018 version.

Your source might be applying a rule that doesn't really apply here.

'When' is a relative pronoun, like 'where' or 'which'. So, you can use 'when' in sentences like this one:

'In 1985, when the movie was first released, more than five million people saw it in theaters.'

In this sentence, 'when the movie was first released' is correctly modifying the noun 1985. 'When' in a modifier should only be used to modify a noun that refers to a specific time.

However, 'when' can also be used as a conjunction. That means it can join two clauses together. That's different from starting a modifier.

For example, you can also use 'when' in sentences like this one:

'When the movie was first released, more than five million people saw it in theaters.'

There are two clauses in this sentence: 'the movie was first released' and 'more than five million people saw it in theaters.' 'When' joins those two clauses together in a logical way. That's what's happening in the sentence you posted. (However, I would use the word 'whenever' instead of 'when', since the sentence is probably referring to something that happens EVERY time the price goes up.)

I found some contradictions in SC resources

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