Some SAT Writing Problems

<p>Can someone please explain these questions because there is no explanations attached?
Pre Thanks.
The words between two smiles are underlined part.</p>

<ol>
<li>Before enrolling in AP Bio, <:-P you should carefully consider what prerequisites are required. <:-P
A. as it is
B. prerequisites that are required should be carefully considered
C. prerequisites should be carefully considered
D. you should consider carefully the required prerequisites
E. he required prerequisites should be carefully considered by you</li>
</ol>

<p>[I am confusing with A and D]</p>

<ol>
<li>:P Our professor :P(A) said that our research papers :stuck_out_tongue: will be due :stuck_out_tongue: (B) on Friday and that :stuck_out_tongue: we should be :stuck_out_tongue: (C) sure to Email :stuck_out_tongue: everything:P (D) by the end of the school day. No error (E)</li>
</ol>

<p>[I chose B but the answer is E, because I thought the verb should be consistent with past tense, can anyone point out why it is wrong and how to avoid future mistakes?]</p>

<p>P.S Although I know a lot about grammar rules, I always make silly mistakes by overlooking some error, is there any way to avoid this. I try to read more carefully, but it results my time is not enough. Such a dilemma!</p>

<p>What are the answers?</p>

<ol>
<li>is a modifier question. The answer must begin with whoever will “enroll in AP Bio,” so it must be a person.</li>
</ol>

<ol>
<li>D, it’s awkward as is, and what marvin100 said</li>
<li>B, should be “would be due”</li>
</ol>