The gyrfalcon, an Arctic bird of prey, has servived a close brush with extionction; its numbers are noe five times greater than when the use of DDT was sharply restricted in the early 1970's.
the number...结构中,谓语动词是要用单数的,为什么这里的its numbers are...numbers会以复数形式出现,its指gyrfalcon这个物种的话,它的数量也应该是个单数才对啊,怎么也想不通,还望大牛们解答,谢谢~~~