andtoestablishsupplybasesbeforeadescentcanbemadeintoaverydeep请帮我分析下beforeadescentcanbemadeinto是什么句型?为什么这样用?thoughanumberofdescentshavebeenmade,muchofitstillremainstobeexplored,请

Question

and to establish supply bases before a descent can be made into a very deep
请帮我分析下before a descent can be made into 是什么句型?为什么这样用?
though a number of descents have been made,much of it still remains to be explored,请问a number of descents have been 跟上面相似，be made 是修饰的吗？但也说不通啊？

Answer 1

before加上一个句子,是时间状语从句,“在...之前”.
though a number of descents have been made尽管已经进行了很多次探险,
been made 不是修饰,是完成时态的被动语态,make a number of descents,所以被动为：a number of descents have been made.