今天翻边了前人的帖子，也没能搞明白，希望NN来帮忙解决一下。

好象整个OG里边只有这2个用了NUMBERS。

152 152. When the technique known as gene-splicing was invented in the early 1970’s, it was feared that scientists might inadvertently create an “Andromeda strain,” a microbe never before seen on Earth that might escape from the laboratory and it would kill vast numbers of humans who would have no natural defenses against it.(A) it would kill vast numbers of humans who would have no natural defenses against it

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

我的问题是，在哪种情况下用NUMBER，在哪种情况下用NUMBERS？

还有 THE OF NUMBER OF XXX IS GREATER THAN YYY。

如果说某数比某数小，要用哪个形容词呢？ LOWER or SMALLER??

请帮忙解答，谢谢

我觉得用smaller更合适