Grasslands in different regions have different names.     1     (cover) one third of the Earth’s surface, grasslands sometimes     2     (know) by many names, such as savannah or plains.

The health of grasslands depends     3     how much animals feed on native plants. If too many animals feed on the plants, the area could become a desert. But too little feeding can also be bad for grasslands.

The Great Plains,     4     are famous for supporting large cattle ranches (畜牧场), cover a large area in the middle of the United States.     5     (make) their businesses more successful by feeding more cattle and sheep without destroying the environment of grasslands, a growing number of local ranchers are joining with     6     (environment) groups willingly nowadays.     7     (compare) with the ranchers, these groups pay more attention to the     8     (protect) of the health of grasslands. And one of their     9     (goal) is to protect native plants and animals. After years of effort, they have increased the income (收入) for local ranches, and at     10     same time, they have protected the Great Plains.

A small town in New Zealand has announced a (n)     1    (usual) plan to ban domestic cats in order to protect native wildlife.

Those     2     currently own cats will not be forced to give them away, according to the plan. However, after their cats pass away, they will not be allowed     3    (get) another one. The cats will need to have microchips (芯片)     4    (put) just below the surface of     5     skins so that they can be found at any time.

Village officials say the plan     6    (need) because domestic cats     7     (attack) wild animals in the area. Because of this, the area’s native wildlife is     8     (rapid) disappearing.

New Zealand has listed 150 animal species as being seriously endangered and in need of     9    (protect). These animals include a kind of ant that only lives under one kind of rock, and a kind of lizard (蜥蜴) that only lives     10     a certain area.

Passenger pigeons once     1     (fly) over much of the United States in unbelievable numbers. Written     2     (account) from the 18th and 19th centuries described flocks (群)so large that they the sky for hours.

It     3     (calculate) that when its population reached its     4     (high) point, they were more than 3 billlion passenger pigeons—a number equal to 24 to 40 percent of     5     total bird population in the United States, making it     6     (true) the most abundant bird in the world. However, the population decreased because of     7     (commerce) hunters who killed them by the thousands. Americans' need for wood scattered the flocks and forced the birds to go farther north,     8     cold temperatures and spring storms contributed to their decline.

In 1897, the state of Michigan passed a law prohibiting the killing of passenger pigeons, only     9     (find) that by then, no sizable flocks had been seen in the state for 10 years. The last of them, known affectionately     10     Martha, died at the Cincinnati Zoological Garden on September 1, 1914.