<p>I have always been taught by my English teachers that when a conjunction (for, and, nor, but, or, yet) is used in the form comma+conjunction (i.e. We paid for six tickets, but we only used three), there must be a full sentence on both sides. Thus:</p>
<p>Correct: We paid for six tickets, but we only used three.</p>
<p>Incorrect: We paid for six tickets, but used three.</p>
<p>Correct: I went to the beach, and I ate three hot dogs there.</p>
<p>Incorrect: I went to the beach, and ate three hot dogs there.</p>
<p>And so on. But I was working through McGraw-Hill’s “Conquering the SAT Writing” and stumbled upon this question (Practice Test 1, Section 2, Problem 2, page 158):</p>
<li>Students too often become preoccupied with (grades, they therefore forget) to examine their knowledge critically.</li>
</ol>
<p>(A) grades, they therefore forget
(B) grades in therefore forgetting
(C) grades; forgetting
(D) grades, and so forget
(E) grades; so they forget</p>
<p>The answer given in the book is (D) grades, and so forget. But putting this into the sentence, we get:</p>
<p>Students too often become preoccupied with grades, and so forget to examine their knowledge critically.</p>
<p>This sounds okay but blatantly defies the grammar rule that my English teachers have taught me! “So forget to examine their knowledge critically” is not a sentence!</p>
<p>Am I missing something?</p>
<p>Please help!
Thank you in advance!</p>