<font color="black">Can you please try to explain this to me or point me to a grammar rule?</font><br/><br/><font color="black">Thank you.</font><br/><br/><font color="black"> </font><br/><br/><b><font color="black">Understanding when to use "at" and when to use "in."</font></b><font color="black"> </font><br/><br/><font color="black"></font><br/><br/><font color="black">I am at the library.</font><br/><br/><font color="black">I am in the library.</font><br/><br/>