Concerns about public health led to the construction between 1876 and 1904 of three seperate sewer systems to serve metropolotan Boston.
B) Concerns about public health have led to the construction of three seperate sewer system between 1876 and 1904 to serve...
here i can't understand why "led" instead of "have led" is used here... why "have led" is not acceptable?
Appreciate NN's reply and advice. Thanks alot!!!作者: James 时间: 2010-4-2 10:26
... Okay, let's talk about your problem here.
The difference between Present Perfect/Continuous Tense, which is normally symbolized by word 'have/has' and past participle of finite verb, and Simple Past Tense, which is normally symbolized by past tense of finite verb, is the beginning time as well as the continuity of such action.
If one action took place in the past with no continuity, normally, we use Simple Past Tense to describe it, whereas, if one action took place in the past with continuity to now, supposedly, we use Present Continuous Tense to do so.
Within this question, the action we have to describe is 'lead',so, if we use Present Continuous Tense -'have led', the description we made will including a implication that those concerns started to lead the construction around 1876, and have kept continuously leading it to nowadays, eventhough the construction was over in 1904.
This doesn't make sense.
Hope it helps.
Have a nice day.
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