<p>When the students take a trip on the intracoastal waterway system next month, they will learn facts with which they have heretofore been unacquainted</p>
<p>a) Fine as it is.
b) facts with which they haven't been acquainted with</p>
<p>According the book, it is fine as it is but I confidently thought it was b. Can someone please explain to me why there's no error? It sounds really awkward and I think B fits better. o_O</p>
<p>B is incorrect because it says “with” twice. A is not really awkward; it’s just a more sophisticated/archaic way of expressing it.</p>
<p>No, there is no error because in answer B, the sentence would end with a preposition. Sentences can never end in a preposition (an object is always needed).</p>
<p>you can’t end a sentence with a preposition</p>
<p>“When the students take a trip on the intracoastal waterway system next month, they will learn facts with which they have heretofore been unacquainted.”</p>
<p>I wonder what a teacher would think if you wrote that monstrosity in a class.</p>