In the previous post on Idiomatic Usage we discussed idioms associated with some words such as hypothesise, considered, comprise, ability and capable. While these are definitely tested on the GMAT it is unlikely that all of these will appear in a single test, not more than one or two will. There are idioms though that will definitely end up making an appearance. These are the less fancy idioms around smaller words that test-takers take for granted (and hence overlook) and that can save them lots of time and help them increase their accuracy. One such word is AS. So many questions are made around this simple word that it deserves a dedicated post.
The questions that test Idiomatic usage are always tricky since if a test-taker is not aware of the idiom he or she can end up spending a lot of time trying to sort out other errors and might be going back and forth between options that are idiomatically incorrect. While it would be easy to give a long list of idioms to learn by rote, a list does not really serve any purpose since the list can become vast and cumbersome and there is no guarantee that you will able to retrieve this idiom from memory when you encounter it. A better way would be to scour the OG and look at the idioms that are consistently tested on the GMAT Sentence Correction.