英语长句分析，较难，高手请进。
However,it is common to hear assertions of the kind " if you were left on a desert island a few seed potatoes would be more useful to you than a million pounds" as though this proved somthing important about money except the undeniable fact that it would not be of much use to anyone in a situation where very few of us are at all likely to find ourselves.
问题1：if引导的是虚拟从句，但是为什么proved也用过去式。
问题2：第二个it在句中做什么成分？
参考答案:as though （或as if) 引导的从句是虚假内容，用过去时和现在时的情况都有，例：
I\'m treated as if I were a spy.
I\'m treated as if I\'m the enemy of the government.
我个人理解,前后时态不一致,大概能更好地强调这种虚假。
第二个it不是形式主语,it就是money.
[it would ...ourselves.]是the fact的同位语从句,the fact等价于这句从句,而不是it等价于前面的长句.
单独分析这句从句:
“money would not be of much use to anyone”是主干,之后的“in a situation”是修饰anyone的定语，再后面的“where very few of us are at all likely to find ourselves”是修饰situation的定语从句
不知道我说清楚了没有