1. We owe a lot to the birds and beasts who eat insects but all of them put together kill only a fraction of the number destroyed by spiders.
    我们要十分感谢那些吃昆虫的鸟和兽，然而把它们所杀死的昆虫全部加在一起也只相当于蜘蛛所消灭的一小部分。

2. Only a small fraction of the creatures that die are preserved in this way before decay sets in or, even more likely, before scavengers eat them.
    死去的生物中也只有一小部分能在开始腐烂前，或更可能在被食腐动物吃掉之前，被这样保存下来。

3. You will hear them often, but it is still widely considered to be improper to use them.
    你会常听到它们,但人们还是普遍认为用它们不妥当;

4. She only spends a fraction of her time at home.
    她在家只呆很少时间.

5. People are only a very small fraction of all the living things on the planet.
    人类只是这个星球上所有生物的一小部分。

6. If you are catching a train, it is always better to be comfortably early than even a fraction of a minute too late.
    如果赶火车，早到总比晚到好，哪怕早到一会儿也好。