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
我再好好地看一遍哈。我这凌晨4点,熬夜写作业。脑子乱,恩,我再来试一次:
结合语义,此题中的led to...to...有cause...to...之意,如果用现在完成时,你体会下,意思是到目前为止还在lead to,逻辑不对。 另外,B改变了原句的时间状语的位置,改变原意: the construction of three separate sewer systems between 1876 and 1904。而原句是 the construction between 1876 and 1904