一套语法题目请教各位大侠！

jameswei0605

Concerns about public health led to the construction between 1876 and 1904 of three separate sewer systems to serve metropolitan Boston.

 

1. Concerns about public health led to the construction between 1876 and 1904 of three separate sewer systems to serve
2. Concerns about public health have led to the construction of three separate sewer systems between 1876 and 1904 to serve
3. Concerns about public health have led between 1876 and 1904 to the construction of three separate sewer systems for serving
4. There were concerns about public health leading to the construction between 1876 and 1904 of three separate sewer systems serving
5. There were concerns leading between 1876 and 1904 to the construction of three separate sewer systems for serving

答案是A

我选的B  为什么不对啊？

谢谢指教！

championxu

没有必要用完成时，

再体会  construction between ... of three separate .... 语序的用法。

LOUI1121

between 1876 and 1904 是过去的一段时间, 不能用过去完成时.