<p>Is this sentence correct?-Forest fires are A boon to the forests.</p>
<p>The following sentences are just written by me. Just to focus on the 'plural' and 'singular' verb.
-My friends or Mary is going to the concert.
-Mary as well as her friends is going to the concert.
-Mary, together with her frineds, is going to the concert.</p>
<p>"Forest fires are A boon to the forests."
I think that's right, but I'm not a grammer expert...</p>
<p>-My friends or Mary is going to the concert. - I'm not sure about this one. It sounds awkward doesn't it?
-Mary as well as her friends is going to the concert.
-Mary, together with her frineds, is going to the concert. - These are correct because the subject is Mary, so the verb should be singular.</p>
<p>-My friends or Mary is going to the concert. - I think the vrb is singular because, its either the friends or Mary is the subject, i guess</p>
<p>-Mary as well as her friends is going to the concert.- I think its 'are' and not 'is' because its mention both of them.</p>
<p>last one is correct</p>
<p>Mary as well as her friends is going to the concert. </p>
<p>would be correct if you added commas:</p>
<p>Mary, as well as her friends, is going to the concert.</p>