【英语时差8,16】如何界定性别？

 When you go to the pet store to pick out a new puppy, one of the first questions you may be asked is whether you want a male or a female. And when your friends have a new baby the first thing you find out is whether it’s a boy or a girl. We may be familiar with the physical differences between male and female in humans and other mammals, but outside of the mammals, the terms “male” and “female” take on some very different meanings. Aristotle defined females as those who could produce life inside themselves and males as those who could produce life in others. But the eggs of some animals, such as fish, are fertilized¹ after they are laid so that the embryos² develop outside of both parents. In other animals, such as earthworms, each individual has both male and female reproductive organs. Animals with both male and female organs are called “hermaphrodites.”

1 Fertilized   

v.施肥( fertilize的过去式和过去分词 )

参考例句：

• The study of psychology has recently been widely cross-fertilized by new discoveries in genetics. 心理学研究最近从遗传学的新发现中受益匪浅。
• Flowers are often fertilized by bees as they gather nectar. 花常在蜜蜂采蜜时受粉。

2 embryos   

n.晶胚；胚，胚胎( embryo的名词复数 )

参考例句：

• Somatic cells of angiosperms enter a regenerative phase and behave like embryos. 被子植物体细胞进入一个生殖阶段，而且其行为象胚。 来自辞典例句
• Evolution can explain why human embryos look like gilled fishes. 进化论能够解释为什么人类的胚胎看起来象除去了内脏的鱼一样。 来自辞典例句