32.One mammal turned out to have a death rate that was even lower than __of many birds:a bat.
问题描述：
32.One mammal turned out to have a death rate that was even lower than __of many birds:a bat.
A that B one C those D ones
答
A. that - 指lower than the death rate of many birds
翻译：有一种哺乳动物被发现具有比许多鸟类还要低的死亡率,那就是蝙蝠.