Since the 1990s, population experts have predicted the number would grow to nine billion before it begins to slow down and possibly decrease.
自20世纪90年代以来，人口专家预测人口数量将增长到90亿，然后增长放慢，甚至可能减少。
2
Low prey population levels then provide inadequate food for the predators, causing the predator population to decrease.
较少的猎物数量为捕食者提供了不足的食物，导致捕食者数量减少。
3
The question of whether the decrease in plant fecundity caused by the spraying of pesticides actually causes a decline in the overall population of flowering plant species still remains unanswered.