Writing MC question

<p>Two questions are from Sparknotes…</p>

<li>(P. 69 #22) Protests for the labor tactics of the national chain of grocery stores forced corporate heads to reconsider their policies toward their employees. No error</li>
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<p>I got this one right by thinking “hmm… B-D don’t seem wrong and since I had #21 as “No Error,” I guess A has something wrong with idioms.” I often do this but this is merely by luck. I’m not native English speaker so idiom is my hardest part. Any good idea on this part? Is there any site that lists commonly used idioms on SAT?</p>

<li>(P. 70 #28) Some critics prefer the inherent artistry of ballet, whereas others are more enthusiastic about its technical perfection. No error</li>
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<p>I didn’t get this one because I put E. The solution says that D should be answer since it’s not right to say “its technical perfection” but rather “technical position of [ballet].” But isn’t “its technical perfection” and “technical position of ballet” mean same thing? I’m guessing this is because of parallelism but I want to be sure.</p>

<p>Thanks!</p>