请教 Prep2012-Pack1-SC-033 VSC001601 谢谢各位高手！

hshbaby

The infant mortality rate has decreased steadily over the past decades and is now at a lower rate than ever before.


A.   now at a lower rate than


B.   now lower than


C.   now a lower rate than


D.   presently lower than it was


E.   presently lower than the rate was


答案如下

B

candy0302

答案答案答案

wickedyyr

看答案~

奕筱坪

加油啊！！！！

右心房的思念

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jjk

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khn7928

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lihaoyang

解释的我看了也很不清楚

花露水6

为什么D不对？
FROM RON：
1) VERB TENSE SHIFT
if there is a change in verb tense between the two halves of the comparison, then you MUST include the verb in both halves. (if the verb is omitted in the second part of the comparison, then the implication is that the tense is the same in both halves.)
so: Heating-oil prices are expected to be higher this year than they were last year --> correct
BUT if you wrote： Heating-oil prices are expected to be higher this year than last year--> incorrect
since there must be a tense shift between what is happening this year and what happened last year.
这里说了有tense shift的话，应该要补出动词的，那这题里省掉的it has been和前面的is不是tense shift吗？
我觉得应该是"The infant mortality rate has decreased steadily over the past decades and is now lower than it has been ever before."
求解释

wdq0305

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