The difficulties that would have to be encountered by any one who attempted to explore the Moon——assuming that it was possible to go there——would be incomparably greater than those that have to be faced in the endeavour to reach the summit of Mount Everest.
参考答案：
要点：该句的主干结构是The difficulties...would be incomparably greater than those...。两个破折号之间的部分是插入语，修饰who引导的定语从句。those指代difficulties。不定式短语to reach...修饰the endeavour。
译文：对于任何试图探索月球（假定到月球是可能的）的人来说，他们要遇到的困难之大，绝非攀登珠穆朗玛峰遇到的困难可以比拟的。
