各位大侠，在js里面如何给一段内容的img标签的src属性的图片路径加上一些字符

【题文】已知双曲线<img src="Upload/2011-10/17/f2f2a395-43af-4f9e-b3c3-b98f3820d00e/paper.files/image001.gif" style="vertical-align:middle;" />的一条渐近线与直线<img src="Upload/2011-10/17/f2f2a395-43af-4f9e-b3c3-b98f3820d00e/paper.files/image002.gif" style="vertical-align:middle;" />垂直,则双曲线的离心率是（&nbsp;&nbsp;&nbsp;）<table name="optionsTable" cellpadding="0" cellspacing="0" width="100%"><tr><td width="25%">A．<img src="Upload/2011-10/17/f2f2a395-43af-4f9e-b3c3-b98f3820d00e/paper.files/image003.gif" style="vertical-align:middle;" /></td><td width="25%">B．<img src="Upload/2011-10/17/f2f2a395-43af-4f9e-b3c3-b98f3820d00e/paper.files/image004.gif" style="vertical-align:middle;" /></td><td width="25%">C．<img src="Upload/2011-10/17/f2f2a395-43af-4f9e-b3c3-b98f3820d00e/paper.files/image005.gif" style="vertical-align:middle;" /></td><td width="25%">D．<img src="Upload/2011-10/17/f2f2a395-43af-4f9e-b3c3-b98f3820d00e/paper.files/image006.gif" style="vertical-align:middle;" /></td></tr></table> 【题文】已知双曲线<img src="Upload/2011-10/17/f2f2a395-4