从句

If I were rich, I should help them out._____I can do nothing. A.As is often the case B.As is it C.As the case is often D.As it is 请给予详细解答！谢谢

解题思路： As it is，If I were rich, I should help them out是一个虚拟语气，翻译为如果我富有，我本应该帮助他们解决困难。._.As it is____I can do nothing.
解题过程：
答案为D.As it is，If I were rich, I should help them out是一个虚拟语气，翻译为如果我富有，我本应该帮助他们解决困难。._.As it is____I can do nothing. 此处As 引导原因状语从句，作“因为，由于”解，与because的用法相近。翻译为因为情形是这样，我什麽也不能做。it 代指the case。现将as作连词，用来连接主句和状语从句情形总结给你，祝你学习进步，节日愉快！有问题讨论！
as作连词，常用来连接主句和状语从句。

1．引导时间状语从句，作“当．．．的时候”解，有“随着．．．”之意，与while意义相近，强调两个动作同时发生；或某事一发生，另一事立即发生。eg：

He shouted aloud as her ran along．他一边往前跑，一边高声地呼喊。

I was startled as he opened the door．他一开门，我吓了一跳。

as作连词，相当于when。eg；

As a little boy (When he was a little boy)he began to learn to play piano．他小时候就开始学弹钢琴。

2．引导原因状语从句，作“因为，由于”解，与because的用法相近。eg；

I must stop writing now，as I have rather a lot of work to do．我必须停笔了，因为我还有许多工作要做。

3．引导方式状语从句或比较状语从句，作“正如，(如)像”解。例eg：

As in your country，we grow wheat in the north and rice in the south．正如(像)你们国家一样，我们在北方种小麦，在南方种大米。(方式状语从句)

When at Rome，do as Romans do．入乡随俗。(方式状语从句)

4．引导让步状语从句，作“虽然，尽管”解。这时从句常用倒装语序，即把从句中的表语、状语或动词原形放在as之前。eg；

Strange as it may seem，it is true．尽管这事看上去很奇怪，但却是真的。

Try as he might，Tom could not get out of the difficulties．不管怎样努力，汤姆还是摆脱不了困境。

最终答案：略