<p>Which is correct:</p>
<p>"Introducing new ideas and replacing old ones is a matter of controversy."</p>
<p>"Introducing new ideas and replacing old ones are a matter of controversy."</p>
<p>And why?</p>
<p>Thanks!</p>
<p>the first one. subject of the sentence is introducing, it is in singular, therefore verb must be in agreement (i.e. uis)</p>
<p>I remember this from the blue book. because "a matter of controversy" is not underlined, you have to go with "introducing... and replacing" as a single subject since "a matter" is a given.</p>