<h2 class="western"><span><span>Must</span></span></h2>
<p><span><span><span>"Must" is most commonly used </span></span></span><span><span><span><em><strong>to express certainty</strong></em></span></span></span><span><span><span>.</span></span></span></p>
<p><span> <span><span>It can also be used </span></span></span><span><span><span><em><strong>to express necessity or strong recommendation</strong></em></span></span></span><span><span><span>, although native speakers prefer the more flexible form "have to." </span></span></span></p>
<p><span><span><span>"Must not" can be used to prohibit actions, but this sounds very severe; speakers prefer to use softer modal verbs such as "should not" or "ought not" to dissuade rather than prohibit.</span></span></span></p>
<p><span><span>Examples:</span></span></p>
<ul>
<li>
<p><span><span>This </span></span><strong><span><span>must </span></span></strong><span><span>be the right address! </span></span><em><span><span>certainty</span></span></em></p>
</li>
<li>
<p><span><span>Students </span></span><strong><span><span>must </span></span></strong><span><span>pass an entrance examination to study at this school. </span></span><em><span><span>necessity</span></span></em></p>
</li>
<li>
<p><span><span>You </span></span><strong><span><span>must </span></span></strong><span><span>take some medicine for that cough. </span></span><em><span><span>strong recommendation</span></span></em></p>
</li>
<li>
<p><span><span>Jenny, you </span></span><strong><span><span>must </span></span></strong><span><span>not play in the street! </span></span><em><span><span>prohibition</span></span></em></p>
</li>
</ul>
<p> </p>
<h2>Using "Must" in Present, Past, and Future</h2>
<p>Most modal verbs behave quite irregularly in the past and the future. Study the chart below to learn how "must" behaves in different contexts.</p>
<table class="collapsible lined">
<tbody>
<tr>
<td>Modal Use</td>
<td>Positive Forms<br />1. = Present 2. = Past 3. = Future</td>
<td>Negative Forms<br />1. = Present 2. = Past 3. = Future</td>
<td>Also use:</td>
</tr>
<tr>
<td>must <br /><em class="comment">certainty</em></td>
<td>1. That must be Jerry. They said he was tall with bright red hair.
<p>2. That must have been the right restaurant. There are no other restaurants on this street.</p>
<p>3. NO FUTURE FORM</p>
</td>
<td>1. That must not be Jerry. He is supposed to have red hair.
<p>2. That must not have been the right restaurant. I guess there is another one around here somewhere.</p>
<p>3. NO FUTURE FORM</p>
</td>
<td>have to</td>
</tr>
<tr>
<td>must not <br /><em class="comment">prohibition</em></td>
<td> </td>
<td>You must not swim in that river. It's full of crocodiles.
<p>You must not forget to take your malaria medication while your are in the tropics.</p>
<p><em class="comment">Prohibition usually refer to the near future.</em></p>
</td>
<td> </td>
</tr>
<tr>
<td>must <br /><em class="comment">strong <br />recommendation</em>
<p>(Americans <br />prefer <br />the form <br />"should.")</p>
</td>
<td>1. You must take some time off and get some rest.
<p>2. SHIFT TO "SHOULD" <br />You should have taken some time off last week to get some rest.</p>
<p>3. SHIFT TO "SHOULD" <br />You should take some time off next week to get some rest.</p>
</td>
<td>1. You mustn't drink so much. It's not good for your health.
<p>2. SHIFT TO "SHOULD" <br />You shouldn't have drunk so much. That caused the accident.</p>
<p>3. SHIFT TO "SHOULD" <br />You shouldn't drink at the party. You are going to be the designated driver.</p>
</td>
<td>should</td>
</tr>
<tr>
<td>must <br /><em class="comment">necessity</em>
<p>(Americans <br />prefer <br />the form <br />"have to.")</p>
</td>
<td>1. You must have a permit to enter the national park.
<p>2. SHIFT TO "HAVE TO" <br />We had to have a permit to enter the park.</p>
<p>3. We must get a permit to enter the park next week.</p>
</td>
<td>1. SHIFT TO "HAVE TO" <br />We don't have to get a permit to enter the national park.
<p>2. SHIFT TO "HAVE TO" <br />We didn't have to get a permit to enter the national park.</p>
<p>3. SHIFT TO "HAVE TO" <br />We won't have to get a permit to enter the national park.</p>
</td>
<td>have to</td>
</tr>
</tbody>
</table>
<table class="collapsible lined">
<tbody>
<tr>
<td>
<p><strong>REMEMBER: "Must not" vs. </strong><strong>"Do not have to"</strong><br />"Must not" suggests that you are prohibited from doing something. "Do not have to" suggests that someone is not required to do something.</p>
<div class="ex">
<p>Examples:</p>
<ul>
<li>You <strong>must not</strong> eat that. <em class="comment">It is forbidden, it is not allowed.</em></li>
<li>You <strong>don't have to</strong> eat that. <em class="comment">You can if you want to, but it is not necessary.</em></li>
</ul>
</div>
</td>
</tr>
</tbody>
</table>