Adjective : The<u> poor</u> should be considered by the government. ( <em>They </em>should...)// The <u>rich </u>should pay higher taxes. The underlined words are functioning as nouns.
Infinitive: <u>To smoke</u> is dangerous. (<em>It</em> is dangerous.)
Gerund: <u>Smoking</u> is dangerous ( <em>It</em> is dangerous..) // I like <u>reading</u> books. (I like <em>it</em>.)
Noun clause: <u>That he is a liar</u> will be in the news. (<em> It</em> will be...) // I do not think <u>that he is married. (</u> I do not think <em>so)</em>
All the underlined elements can be subtituted for a <em>pronoun</em> or <em>so</em> : personal or impersnal. Look at the information in parentheses. <em>So </em>replaces a noun clause when the noun clause comes after a verb like "to think".
