一道英语语法题求详解.IftheUnitedStateshadbuiltmorehomesforpoorpeoplein1955,thehousingproblemsnowinsomepartsofthecountrysoserious.A.wouldn'tbeB.wouldn'thavebeenC.willnotbeD.wouldhavenotbeen为什么答案

Question

一道英语语法题求详解.
If the United States had built more homes for poor people in 1955,the housing problems now in some parts of the country__ so serious.
A .wouldn't be
B .wouldn't have been
C .will not be
D .would have not been
为什么答案是A?B哪里不对了?前面有had done 所以后面用would+V.

Answer 1

如果美国政府在1955年的时候为广大贫民修建更多的房屋,也不至于现在的住房问题还是这么严峻.
可以这样理解,肯定用would的否定式,A的意思是从1955年起,到现在,持续的将来,居住问题会一直严峻.
B是现在完成时,意思是说1955年以来,住房问题持续到现在,按现在完成时的意思,将来就没有这样的问题了.
很显然这严峻的问题会延续下去,所以不能用现在完成时,而该用一般时态.
反正我是这样分析的,信不信由你,反正我是信了.