It is impossible to give a satisfactory explanation for a potholer 's motives .

要对洞穴探险者动机作出满意解释是不可能。

It is impossible to give a satisfactory xplanation for a potholer 's motives .

要对洞穴探险者动机作出满意解释是不可能.

The cave might never have been discovered had not the entrance been spotted by the distinguished french potholer .

如果不是被著名的法国洞穴勘探家柏杰看到，这个洞穴可能永远不会被人发现。