He will say so, and you may disagree with him too - politely, of course!
你也可能会不同意他的看法——当然,你应该礼貌地告诉他。
The cave might never have been discovered has not the entrance been spotted by the distinguished French pot-holer, Berger.
若不是法国著名洞穴探险家伯杰由于偶然的机会发现了这个洞口的话,这个洞也许不会为人所知。