2-9. One authority on spiders made a census of the spiders in grass field in the south of England, and he estimated that there were more than 2,250,000 in one acre; that is something like 6,000,000 spiders of different kinds on a football pitch.

【译文】

某蜘蛛权威对英国南部某块草坪上的蜘蛛数目统计了一次。他估计每英亩草坪里有超过225万只蜘蛛，即相当于一个足球场上约有6百万只种类各异的蜘蛛。

【单词和短语】

authority：学术权威，专家，泰斗（someone who knows a lot about a subject and whose knowledge and opinions are greatly respected）。某方面的authority需用介词on，

例如：
an authority on preventive medicine 预防医学的权威

something like：接近，大约（close to but not exactly a large amount），

例如：
He is to sell the house for something like $150,000.

他将以大约15万美元的价钱出售这幢房子。

census：统计数量（a process of counting something）。

2-10. Spiders are busy for at least half the year in killing insects.

【译文】

蜘蛛至少有半年在忙于吃虫。

【讲解】

half（形容词）the year是half（名词）of the year的省略形式。

2-11. It is impossible to make more than the wildest guess at how many they kill, but they are hungry creatures, not content with only three meals a day.

【译文】

它们消灭了多少昆虫，我们简直无法猜测，它们是吃不饱的动物，不满足于一日三餐。

【讲解】

it是形式主语，真正的主语是to make more than the wildest guess at how many they kill。It is impossible to…是重点句型，需熟练掌握。not前省略了and they are。

【单词和短语】

content：adj. 满意，满足（happy and satisfied）。

2-12. It has been estimated that the weight of all the insects destroyed by spiders in Britain in one year would be greater than the total weight of all the human beings in the country.

【译文】

据估计，在英国一年里被蜘蛛消灭的昆虫的总重量超过该国人口的总重量。

【讲解】

it是形式主语，真正的主语是the weight of all the insects destroyed…in the country。It has been estimated that…是重点句型，需熟练掌握。