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.
參考答案：

要點(diǎn)：該句的主干結(jié)構(gòu)是The difficulties...would be incomparably greater than those...。兩個(gè)破折號(hào)之間的部分是插入語(yǔ)，修飾who引導(dǎo)的定語(yǔ)從句。those指代difficulties。不定式短語(yǔ)to reach...修飾the endeavour。

譯文：對(duì)于任何試圖探索月球（假定到月球是可能的）的人來(lái)說(shuō)，他們要遇到的困難之大，絕非攀登珠穆朗瑪峰遇到的困難可以比擬的。