请教GWD2-11

GWD3-Q11:

Retailers reported moderate gains in their November sales, as much because of their sales of a year earlier being so bad as that shoppers were getting a head start on buying their holiday gifts.

1. of their sales of a year earlier being so bad as that
2. of their sales a year earlier having been as bad as because
3. of their sales a year earlier being as bad as because
4. their sales a year earlier had been so bad as because
5. their sales of a year earlier were as bad as that

答案是：D

很难想到这个答案，had been的时态很奇怪的，as....as当中出现一个so...这个题目为啥这么选呢？

哇。。。真是感动bz那么晚还在帮助解答问题。。。

下次问问题前先去百度查查：）谢谢啦