Anyone understand this Writing Question: Spot the Error!

<p><a href="A">u</a> When L'Enfant suggested <a href="B">u</a> to build the United States Capitol</p>

<p><a href="C">u</a> at the center of Washington, D.C., he also <a href="D">u</a>offered to design</p>

<p>a landscaped mall nearby. <a href="E">u</a> No error</p>

<hr>

<p>I put (E) No Error. Why is it (B) to build?</p>

<p>suggested building</p>

<p>suggested building
hoped to build</p>

<p>gotta kno these</p>

<p>why is it progressive tense? i thought the verb is supposed to infinitive for subjunctives?</p>

<p>its just the way it is. idioms kind of.</p>

<p>ok. thanks.</p>

<p>can you also clarify when it would be appropriate and inappropriate for using “although”</p>

<p>not progressive tense
gerund</p>

<p>woo i love writing like this</p>

<p>yeah gerund. forgot.</p>