Li Chunru,    1    72-year-old retired doctor in a village in East China's Jiangxi Province, has been voluntarily taking care of wild birds at Poyang Lake Nature Reserve for over 30 years, bringing over 50, 000    2    (wound) birds out of danger.

For the past 36 years, Li Chunru woke up at 5 o'clock in the morning every day and walked along Poyang Lake regularly, protecting birds from any    3    (harm)human activity. Li is among a group of volunteers    4    came forward to protect the wild birds from illegal(不合法的)activities that are endangering the existence of some species in the area. His selfless    5    (devote) to the bird protection started one day 30 years ago, when a storm destroyed the birds' nest near his house,    6    (leave) the birds scattered around. Li was    7    (deep) struck by the scene and saved 310 out of the 370.

At first, Li's work was not understood by the    8    (villager) including his family. But Li never gave up. Instead, he kept convincing them with the knowledge of the law for environmental protection. His efforts finally paid off-more and more people started to accept Li's faith and voluntarily joined the team    9    birds' protection. And the aim of stopping illegal activities around Poyang Lake    10    (achieve) in 2017.

Can Indoor Plants Really Purify the Air?

Plants are very important to human life. Through photosynthesis (光合作用), they transform carbon dioxide into fresh oxygen. They     1    (assume) to remove toxins from the air we breathe—but is this true?

One famous NASA experiment, published in 1989, has found indoor plants can clean the air by removing pollutants     2    (cause) cancer. Later research has found soil micro-organisms in the potted plant also     3    (play) a part in cleaning indoor air.

Based on this research, some scientists say house plants are effective natural air purifiers, and the bigger and leafier the plant, the better. The amount of leaf surface area influences the rate of air purification.     4    , however, say the evidence that plants can effectively accomplish this feat (功绩) is far from conclusive.

“There are no definitive studies to show that having indoor plants can significantly increase the air quality in your home,”     5    Luz Claudio, a professor of environmental medicine and public health. “There’s no question     6    plants are capable of removing volatile (易挥发的) chemical toxins from the air under laboratory conditions,” says Claudio. But in your home or office space, the notion that putting a few plants together can purify your air doesn’t have much hard science     7    (back) it up.

Most research efforts to date, including the NASA study, placed indoor plants in small,     8    (seal) environments to assess how much air-purifying power they have. “But those studies aren’t really applicable to what happens in a house. In many cases, the air in your home completely turns over—that is, exchanges places with outdoor air—once every hour. In most instances, air exchange with the outside has a     9    (great) effect on indoor air quality than plants.” says Stanley Kays, a professor of horticulture (园艺学).

Disappointed     10    many people may be by what Kays said, the professor also made it clear that he believes house plants are beneficial. Studies have shown plants can knock out stress and make people feel happier. More research shows spending time around nature has a positive effect on a person’s mood and energy levels.

Haven’t you always wondered why the beginning and the end of the present school year don’t line up with the calendar year? Well,     1     answer might surprise you: the school year actually     2     (date) back to the time when the farming schedule took     3     (prior) over everything else — even schooling.

Farming can only be done in spring, summer, and fall. Families needed kids’ help, so their schooling took place in the colder months     4     nothing could be planted or harvested. Thus kids could help with farm duties during busy seasons.

Large cities operated     5     (different). Because people there didn’t rely on farming     6     (earn) a living, kids could go to school all year round and take a few short vacations throughout.

When education started to become more valuable in society, much       7     (strict) rules had to be made so that there would be more uniformity in the school system. In 1852, Massachusetts became the first state to enact a compulsory public law, making it compulsory     8     both rural areas and urban areas to offer schooling. Parents     9     (fine) if they didn’t send children to schools.

Shortly after Massachusetts enacted the law, a compromise     10     (make) between urban and rural school systems let the school year start in the fall so kids could help with farming during the summer.