<p>Could someone explain the following problems to me:</p>
<p>Pg. 479, #16:</p>
<p>(Along) the cruve of the islands known as the Florida Keys (lies) a reef of living coral, (the onle one) of (a kind) in the continental United States. (No error).</p>
<p>The correct answer is (a kind), but I cannot see at all why that is (The sentence is very awkward, yes, but I don't know specifically what is wrong/why it is wrong). I marked no error.</p>