Two Grammar Question

<ol>
<li>(Because of opening the floodgates), the water level of the reservoir stopped rising.</li>
</ol>

<p>VS</p>

<p>(After the floodgates were opened), the water level of the reservoir stopped rising.</p>

<p>The latter is the correct one. But why? I thought both of them were fine.. What is this error?</p>

<ol>
<li>Many scientists (concerned) about the danger of radioactive waste (believe) that nuclear reactors using fusion would be preferable (over) (those) using fission.</li>
</ol>

<p>The answer is (over). Why? Should it be than? Why can't it be over those using fission? In it unidiomatic?</p>

<ol>
<li><p>You really shouldn’t start a sentence with because, it’s almost always wrong. I don’t know how to explain it technically, but it’s improper grammar to say “because of opening.”</p></li>
<li><p>I believe it has to be (to). Although it sounds correct, and I would have said there was nothing wrong with it, I guess (over) just isn’t good english. :)</p></li>
</ol>

<ol>
<li><p>you have to say who opened it. otherwise it doesn’t make sense</p></li>
<li><p>preferable over is wrong. i guess its an idiom</p></li>
</ol>

<p>i still don’t quite get it :/</p>

<p>Because is a conjunction. Conjunctions are linking words. Don’t start a word with because.</p>

<p>BUt sometimes the right answer starts with Because (in fact when I was doing a practice test today, one of the right answer does start with BECAUSE!)</p>

<p>So I don’t think it’s a really valid rule for the SAT :(</p>

<p>there’s no subject</p>

<p>Do you always need a subject in an introductory phrase?</p>

<p>Never start a sentence with “because”</p>

<p>no, but this sentence says that it was opened by someone but it doesn’t say who</p>

<p>I also learnt a rule to not open a sentence with “due to”
I think “because of” should be replaced by “due to” but then u cant start a sentence with due to.</p>