251. The gyrfalcon, an Arctic bird of prey, has survived a close brush with extinction; its numbers are now five times greater than when the use of DDT was sharply restricted in the early 1970's. .
(A) extinction; its numbers are now five times greater than
(B) extinction; its numbers are now five times more than
(C) extinction, their numbers now fivefold what they were
(D) extinction, now with fivefold the numbers they had
(E) extinction, now with numbers five times greater than
这个 题就是个反例吧!!
此題A為正確答案,比較的是主語,若如前所說,前后時態不一緻應該補全,即應為:its numbers are now five times greater than it was when the use of DDT was sharply restricted in the early 1970's.