重新讨论一下885-sec 1-24

24.   Even though its per capita food supply hardly increased during two decades, stringent rationing and planned distribution have allowed the People’s Republic of China to ensure nutritional levels of 2,000 calories per person per day for its population.

(A) Even though its per capita food supply hardly increased during

(B) Even though its per capita food supply has hardly increased in

(C) Despite its per capita food supply hardly increasing over

(D) Despite there being hardly any increase in its per capita food supply during

(E) Although there is hardly any increase in per capita food supply for

The key is B. Any one can tell the reason that B is better than A?

Thanks

two decades是一段时间，所以应该用完成时态，后面的主句用的是have allowed，现在时态，而原句中也没有明显的表示过去的时间状语。所以时态和主句时态保持一致。就是has increased。

注意这里的its指代。借鉴一下ETS是怎样消除指代不清问题的。

多谢。还有一个为题。during 前面是否只能用过去时？ 按字面理解，during 应该是在一段期间。但是我看了很多题干和例句，都是接的过去时，没有完成时。很想得到确认，during 只能用过去时，或者是也可以用完成时，但要根据具体情况。