//*[count(ccc)=2]
Select all elements which have two children "ccc"//*[count(ccc)=2]
... <aaa> <bbb> <ccc></ccc> <ccc></ccc> </bbb> </aaa> ...
Select all elements which have two children "ccc"//*[count(ccc)=2]
... <aaa> <bbb> <ccc></ccc> <ccc></ccc> </bbb> </aaa> ...