I would really advise you against this approach. The focus of GMAC on testing idioms has significantly reduced. In fact the more optimum approach is to eliminate the choices based on more deterministic errors first and then if need be in the end use the idioms based errors for elimination.
The problem with learning what are wrong idioms is that there is a vast array of idiomatic usage. Let's take "so weak as".
Incorrect - Mary is so weak as her mother claims.
This may be incorrect in certain context but when used in the context of "so weak as to verb", it may be correct as I noted in my post above. So while learning the incorrect idioms, you may end up overloading your brain unnecessarily with all the usages when in fact you could be following a much more scientific way of approaching Sentence Correction. After all it is not GMAC's intention to see how well you can cram things. In fact since idiomatic usage is very country specific, it will be unfair to test American Idioms in a test that has an international reach.
So I would suggest you do not focus on learning incorrect idioms. Tackle SC the way it is designed to be tackled. Understand the meaning to be communicated and then determine if the sentence has been written in grammatically correct form. If not, then select the choice that is indeed written in correct form and that communicates the meaning that needs to be communicated. I will end with a direct quote from official guide
Pay close attention the part in blue. This statement is addition in OG13.The questions ask you to select from the answer options the best expression of the idea or relationship described in the underlined section....Sentence correction questions may include English-language idioms, which are standard constructions not derived from most basic rules of grammar and vocabulary, but idioms are not intended to measure any specialized knowledge of colloquialisms and regionalisms.
Hope this helps.
Regards,
Payal
