Answer:
<em>The sentences </em>A: <em> While she was studying, her dog began to lick her elbow. </em>and<em> </em>D:<em> Without a doubt, she was the fastest in her heat.</em>
Explanation:
The senteces A and D are correct because both begin with a <em>subordinate</em> clause, therefore they have <em>commas</em> to <em>separate them from the main clauses</em>. The sentence B is wrong because it is <em>not necessary</em> the use of the <em>comma</em>, since it started with the main clause. and in the sentence C, the transitional word <em>however</em>, doesn't have another statement to contrast with.
Rainsford's actions are justified because he will never truly be free until Zaroff is dead. A "beast at bay" refers to someone who is still being hunted. Rainsford will always feel hunted as long as Zaroff is alive, because he knows the 'hunt' will always go on in Zaroff's mind. He has to kill Zaroff so he doesn't have to live in fear.
Prevalent means widespread, dominant
Flu is prevalent in the wintertime as many people catch it.