<p>Here's a question form the BB book. Which part of the underlined sentence...</p>
<p>Introducing new ideas and replacing old ones is always a highly controversial matter, especially when there is already tension between an older ad a younger generation.</p>
<p>(A)Introducing
(B) old ones
(C)is
(D) especially when
(E)No error</p>
<p>Isn't the sentence itself wrong, because it's supposed to be 'are' instead of 'is' (the clause - introducing AND replacing), but you can not choose C because you have 'a highly controversial matter' in singular not underlined, which mens that it has to be correct. In my opinion he sentence should be 'Introducing new ideas and replacing old ones are always controversial matters...'</p>
<p>What do you guys think about that?</p>