View source for Bu and mei(you)

Although 不 (bù) and 没(有) (méi(yǒu)) both have the same functions of negating verbs and adjectives, they are used differently. Let's take a look at some of these differences. 

==有 is negated with 没==

没 (rather than 不) is always used to negate 有, the verb meaning "to have."  The phrase "不有" exists only in non-standard Chinese dialects, in obscure set phrases (that you don't need), and in incorrect Chinese.  Keep in mind also that when 没 is used to negate 有, 有 can be dropped altogether.

<div class="liju">

<ul>
<li class="o">没有</li>
<li class="x"><strong>不</strong> 有</li>
<li class="o">我 没有 钱。</li>
<li class="o">我 没 钱。</li>
<li class="x">我 <strong>不</strong> 有 钱。</li>
<li class="o">她 没有 朋友。</li>
<li class="o">她 没 朋友。</li>
<li class="x">她 <strong>不</strong> 有 朋友。</li>
</ul>

</div>

==Past and present statements==

Perhaps the most important difference between 不 and 没(有) is that 不 negates actions and statements about the present whereas 没 negates actions and statements about the past.  Note that 没(有) is used to say that something ''has not taken place'', whereas 不 is used to say that something ''is not'' the case, or ''will not happen''. 

For example:

<div class="liju">
* 我 <em>不</em> 去。 <span class="expl">I won't go; I'm not going)</span>
* 我 <em>没</em> 去。 <span class="expl">I didn't go)</span>
* 我 <em>没</em> 告诉 他！ <span class="expl">I didn't tell him)</span>
* 我 <em>不</em> 告诉 你！  <span class="expl">I won't tell you; I'm not telling you)</span>
</div>

==A few exceptions==

The verb 是 is never negated with 没; it can only be negated with 不.

<div class="liju">

<ul>
<li class="o"><em>不</em> 是</li>
<li class="x"><strong>没</strong> 是</li>
<li class="o">昨天 <em>不</em> 是 星期一。</li>
<li class="x">昨天 <strong>没</strong> 是 星期一。</li>
<li class="o">那个 时候，我们 <em>不</em> 是 朋友。</li>
<li class="x">那个 时候，我们 <strong>没</strong> 是 朋友。</li>
</ul>

</div>

== Sources and further reading ==

=== Websites ===

* http://www.docin.com/p-20925643.html
* http://wenku.baidu.com/view/e2e8eb2ce2bd960590c67703.html