<i>I am going to the mall as I did yesterday.</i><br/><br/>Is that a compound sentence?<br/><br/><i>I am as tall as he is.</i><br/><br/>Is as an adverb or an adjective?<br/><br/><i><br/>He's talking to me as if he doesn't know me.</i><br/><br/>What is "as if"? Prepositional phrase?<br/><br/>Thank you for answering.