王志剛

許多年前，農(nóng)民為保護(hù)他們的雞而獵殺了很多老鷹。 然而新問題來了，田里的田鼠猖獗了起來，結(jié)果農(nóng)民的莊稼大多給吃光了。這是怎么回事呢？看看下文你就知道了。

Not ?many ?years ?ago， ?some ?farmers ?were worried ?because ?hawks ?were ?taking many ?of their ?chicken. ?The ?farmers didnt ?know ?what ?to ?do. ?Finally they went ?to ?the ?country officials ?and ?asked ?for ?help.

“Kill ?the hawks，” the ?officials ?said，“ we ?will ?even ?pay ?for ?them. ” So ?the ?farmers ?began ?to ?think ?of ?ways ?to ?kill the hawks.

The ?farmers ?killed ?many ?hawks. ?They ?no ?longer ?had ?to ?worry ?about ?their ?chickens. But ?they ?now ?had ?a ?new ?worry. Field ?mice ?were ?eating ?up ?a ?lot ?of ?the ?farmers ?grain.

How ?did ?this happen？

Hawks ?ate ?not ?only ?chickens ?but ?also ?field ?mice. ?They ?ate ?more ?field ?mice ?than ?chickens. ?But ?the ?farmers ?didnt ?know ?this. ?When ?they ?killed ?a ?lot ?of ?hawks， ?they ?changed ?the balance.

When people move into a new place， ?they often ?destroy ?many ?wild plants. ?Often these plant are food for the animals. If the animals cant find enough plants to ?eat， they ?will starve or ?have ?to leave ?the place.

In one part of ?the ?USA， ?for ?example ?the ?deer ?there ?like ?to ?eat ?a ?certain ?kind ?of ?wild ?roses. ?The ?mountain ?lions ?there ?eat ?the ?deer. ?The number ?of ?deer， ?mountain ?lions ?and wild ?roses ?doesnt ?change ?much ?if ?people ?leave ?things ?as ?they ?are.

But ?people ?killed ?many ?mountain ?lions ?in ?order ?to ?protect ?the deer. ?Soon ?there ?were so many deer that they ate ?up ?all ?the wild ?roses. ?Then ?the ?deer ?began ?to ?eat ?the ?green ?leaves of young trees. These trees ?were ?important ?to ?the ?farmers. ?So ?the ?farmers thought ?of ?ways ?to ?protect ?their ?trees. Now ?the ?deer had ?nothing ?to ?eat， ?and many ?of ?them ?died. This ?was ?another ?lesson ?from ?nature.