<p>I need help understanding </p>
<p>Whom vs Who</p>
<p>Which vs That</p>
<p>Who is for the subject and whom is for the object. Example, </p>
<ol>
<li><p>The three bank robbers, two of “whom” are still unidentified, stole over $500,000 from the bank vault. The three bank robbers are the subject, the two are the object therefore you use “whom.”</p></li>
<li><p>My teacher, “who” was Ukrainian, spoke with a thick accent, which made her difficult to understand. The teacher is the subject, therefore “who” is proper.</p></li>
</ol>
<p>Gener rule of thumb: Substitute the personal pronoun “he” for “who” and “him” for “whom.” If “he” would be the correct form, the proper choice is "who.” If “him” would be correct, use “whom.” </p>
<p>-iBP</p>
<p>Sorry this may sound quite silly but how do you know when it is an object and when it is the subject?</p>