button对应的代码如下：
<image class="imageButton" border="0" onclick="addActivities()" name="adding" src="images/add_set.gif"/>
1. 如何判断这个button在页面上存在？
2. 如何才能点击这个button？

谢谢

In fact, it is really simple, why does nobody reply it?
$ie.image(:src, /.../).click is OK!
I really think that, we can be generous!

Sorry mate, did not see your post.
But, as you have said, it's simple, isn't it? It will take you less than 5 minutes to find it out in watir API