大家帮我看看这道题吧

[MrKBoard]

Please study the tutorials for XML and XML query language, and discuss whether the following queries in each of the group below are equivalent and why.
Group1:
Q1: //book[./author/firstname = “Mike” and ./author/lastname = “Stonebraker”]
Q2: //book[./author[./firstname = “Mike” and ./lastname = “Stonebraker”]]
Q3: //book/author[./firstname = “Mike” and ./lastname = “Stonebraker”]
Q4: //book[./author[./firstname = “Mike” and ./lastname = “Stonebraker”]]/author
Group 2:
Q1: //book[./author/firstname = “Mike” and ./author/lastname = “Stonebraker”]/author[2]
Q2: //book/author[2][./firstname = “Mike” and ./lastname = “Stonebrake”]
Q3: //book[./author[2][./firstname = “Mike” and ./lastname = “Stonebrake”]]/author

[cds27]

Group1中，q1和q2相等，返回相同的book。
q3和q4返回author，但不相等。q4的集合包含q3。

Group2中，全部不相等。

[ganlianter]

//当前选择节点下的所有节点
.当前节点
随便讲一条
//book[./author/firstname = “Mike” and ./author/lastname = “Stonebraker”]/author[2]
根据实际情况
可能是这样的一个xml
<book>
<author>
<firstname />
<lastname />
<author>
</book>
这个xquery就是找到所有记录中firstname叫mike而且lastname叫stonebraker的所有book集合的author第二深度的节点
好像很绕口=。=这个应该蛮复杂了