You can use a pseudo-element to insert that character before each list item:
ul {_x000D_
list-style: none;_x000D_
}_x000D_
_x000D_
ul li:before {_x000D_
content: '?';_x000D_
}
_x000D_
<ul>_x000D_
<li>this is my text</li>_x000D_
<li>this is my text</li>_x000D_
<li>this is my text</li>_x000D_
<li>this is my text</li>_x000D_
<li>this is my text</li>_x000D_
</ul>
_x000D_