by tim Mon Jun 30, 2014 11:05 pm
Although I agree with Ron that there are idioms here, my advice is to avoid idioms whenever possible and only deal with idioms as a last resort when no other grammar rules apply. As such, idioms here are not an issue in the sense that they are not needed to make the decision you were asking about.
As Ron indicates, it is almost certainly easier to use S-V agreement on a sentence such as this. S-V issues are more concrete than idioms and have blanket rules to cover their application, and you're much more likely to make a correct decision if you stick to the hard and fast grammar rules.
In this particular case, Ron has given an excellent explanation of the specific idioms used here, but it is important to keep in mind that you cannot derive from this explanation any rules about whether "determined from" and "determined through" are correct idioms in general. It will all depend on the context.
Tim Sanders
Manhattan GMAT Instructor
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