help me , grammar question please! SAT

<p>okay, here.
1- Remarkable breakthroughs in gene research may lead to dramatic changes in medical (treatment, where it may be possible to create) drugs tailored to a patient's genetic makeup.</p>

<p>the correct answer is : (treatment by making it possible to create)
okay , what does (it) refers to ?
why does the choices d and e are wrong ?
d-treatment that makes it possible creating
e-treatment that makes possible creating? </p>

<p>2- (we had never seen) anything like this style before , we thought we were looking at giant sculptures,not buildings.</p>

<p>correct answer is : never having seen .
why not :
1- the original form ( we had never seen)
2- we never saw
3-never had we seen
4-never seeing.
help me , pleaseee :0</p>

<ol>
<li>“It” doesn’t have to refer to anything. It is a English teacher pet peeve to consider vague "it"s as incorrect, although it is common for “it” to be used without referring to a subject. See?</li>
</ol>

<p>D is incorrect because “creating” needs to be “to create”.
E is incorrect because “makes possible creating” is grammatical nonsense.
You should be able to tell they are wrong by using your grammar ear- do they “sound” right? No.</p>

<p>Anyways, “by” is the correct word here. How are drastic changes made? BY making it possible to make special drugs.</p>

<ol>
<li>You do not want the first clause to be independent, because a comma won’t connect them correctly then. That’s why 1 and 2 are wrong. 3 is not in the right tense. 4 is wrong by grammatical convention. Trust your grammar ear on this.</li>
</ol>