LINKS
Markdown supports two style of links: inline and reference.
In both styles, the link text is delimited by [square brackets].
To create an inline link, use a set of regular parentheses immediately after the link text’s closing square bracket. Inside the parentheses, put the URL where you want the link to point, along with an optional title for the link, surrounded in quotes. For example:
This is [an example](http://example.com/ "Title") inline link.
[This link](http://example.net/) has no title attribute.
Will produce:
<p>This is <a href="http://example.com/" title="Title">
an example</a> inline link.</p>
<p><a href="http://example.net/">This link</a> has no
title attribute.</p>
If you’re referring to a local resource on the same server, you can use relative paths:
See my [About](/about/) page for details.
Reference-style links use a second set of square brackets, inside which you place a label of your choosing to identify the link:
This is [an example][id] reference-style link.
You can optionally use a space to separate the sets of brackets:
This is [an example] [id] reference-style link.
[a](a a)不可以，因为括号直接有空格