Concerns about public health led to the construction between 1876 and 1904 of three separate sewer systems to serve metropolitan Boston.
A. Concerns about public health led to the construction between 1876 and 1904 of three separate sewer systems to serve
B. Concerns about public health have led to the construction of three separate sewer systems between 1876 and 1904 to serve
C. Concerns about public health have led between 1876 and 1904 to the construction of three separate sewer systems for serving
D. There were concerns about public health leading to the construction between 1876 and 1904 of three separate sewer systems serving
E. There were concerns leading between 1876 and 1904 to the construction of three separate sewer systems for serving
答案为A，我选B
我的问题是:
1.A B 仅是时态上的差异吗？ 我是，我偏向现在完成时，强调对现在的影响
2.此处时间状语的位置有无讲究？
谢谢牛牛 | 
