A teacher gave his     1    (pupil) some sunflower seeds to let them learn to look after a plant.One boy in the class,    2     loved sunflower seeds,was very excited.He planted the seed and looked after it    3    great care for many days. 

When the first shoot(嫩芽) finally appeared,the boy,    4     (fill) with impatience,went to see his teacher.The teacher said that he would still have to take care of the plant for quite some time before he was able to collect many seeds from just one sunflower.The boy was    5    (disappoint),but he kept     6    (look) after his sunflower. 

However,he grew     7    (increasing) impatient,and did little else but pester(纠缠) his teacher for wanting to take out the plant.As soon as the boy saw the sunflower’s first seeds,he cut the plant.But the plant was still green,and of course the seeds couldn’t    8    (eat). 

The boy was annoyed.He had put so much effort into     9    sunflower,but in the end he wasted it all for his impatience.And he was even     10    (angry) when he saw how big his classmates’ sunflowers grew.Finally,he decided not to be so impatient any more.

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

It     3    （calculate）that when its population reached its     4    （high）point, there were more than 3 billion 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 tried to pass 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.

Covering an area about three times     1     size of Yellowstone National Park, the GPNP is designed to reflect the guiding principle of “protecting the authenticity and integrity (完整性) of natural ecosystems, preserving biological diversity, protecting ecological buffer zones,     2     leaving behind precious natural assets (资产) for future generations”.

Giant pandas also serve     3    an umbrella species (物种), bringing protection to a host of plants and animals in the southwestern and northwestern parts of China.