One early 20th-century big-top act featured 75 polar bears at once.
20世纪早期的一次大戏以一次展出75头北极熊而著称。
2
Mathematical models have also revealed that food webs may be unstable, where small changes of top predators can lead to big effects throughout entire ecosystems.
数学模型也揭示了食物网可能是不稳定的，顶级肉食性动物的微小改变会对整个生态系统产生巨大影响。
3
At a big meeting of top British businesspeople, he stood up and explained the secret of his success.