A closer look at the fertility behavior of the poor is important because of the extensive literature on the "replacement effect" of high infant mortality.
仔细研究穷人的生育行为是很重要的，因为有大量关于婴儿高死亡率的“替代效应”的文献。
2
And helping behavior can even be seen in infant chimpanzees under the right experimental conditions.
而且在适当的实验条件下，黑猩猩幼崽也会表现出这种助人行为。
3
Objective To explore the effects of early education on infantbehavior development and design a efficient early education mode.