Directions: After reading the passage below, fill in the blanks to make the passages coherent and grammatically correct. For the blanks with a given word, fill in each blank with the proper form of the given word; for the other blanks, use one word that best fits each blank.Can Indoor Plants Really Purify (净化) the Air?
Plants are very important to human life. Through photosynthesis (光合作用), they transform carbon dioxide into fresh oxygen. They 【小题1】 (believe) to remove toxins (毒素) from the air we breathe — but is this true?
One famous NASA experiment 【小题2】 (publish) in 1989 has found indoor plants can clean the air by removing pollutants 【小题3】 cause cancer. Later research has found soil micro-organisms in the potted plant also 【小题4】 (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. 【小题5】, 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 【小题6】 (have) indoor plants can significantly increase the air quality in your home,” According to Luz Claudio, a professor of environmental medicine and public health. “There’s no question that 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 idea that putting a few plants together 【小题7】 purify your air doesn’t have much hard science to support it.
Most research efforts so far, including the NASA study, placed indoor plants in small, sealed environments to assess how much air-purifying power they have. “But those studies aren’t really applicable to what happens in house, 【小题8】 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 【小题9】 (great) effect on indoor air quality than plants.” says Stanley Kays, a professor of horticulture (园艺学).
Disappointed as many people may be by what Kays said, the professor also believes 【小题10】 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.