<p>question 14 on page 846:
<em>Introducing</em> new ideas and replacing <em>old ones</em> <em>is</em> always a highly controversial matter, <em>especially when</em> there is already tension between an older and a younger generation.</p>
<p>I know this is a simple question, and the answer is E, but can someone please explain why exactly is the two gerunds together singular?
Thanks</p>