题干

薇甘菊是多年生藤本植物,在其适生地能攀援、缠绕于乔灌木,重压于其冠层顶部,阻碍附主植物的光合作用,继而导致附主死亡.因此,薇甘菊是世界上最具危险性的有害植物之一.科研人员研究了薇甘菊不同入侵程度对深圳湾红树林生态系统有机碳储量的影响,结果如表.请分析回答:

有机碳含量/t•hm﹣2

未入侵区域

轻度入侵区域

重度入侵区域

植被碳库

51.85

50.86

43.54

凋落物碳库

2.01

3.52

5.42

土壤碳库

161.87

143.18

117.74

总计

215.73

197.56

166.70

上一题 下一题 0.0难度 选择题 更新时间:2011-03-14 09:59:30

答案(点此获取答案解析)

同类题5

根据短文理解,选择正确答案。
A
    Shopping used to mean actually going to shops, but nowadays, you can shop without even leaving your house. Just sit in front of your computer, click your mouse and your things will be sent to your house in a couple of days.
November 11th is a big day for people who like shopping online. On that day last year, many online stores offered a big discount and free delivery service. The biggest online shopping sites in China, Taobao. com and Tmall.com, sold things worth 19.1 billion yuan in total.
    “Goods online are often much cheaper. It also saves me a lot of time. And we often have more goods on many online stores than in shopping malls,” Wang Xin, an online shopping lover in Beijing, said to China Daily. She stayed up very late for a lot of cheap goods online. She spent several thousand that day.
    Another big advantage of online shopping is that it helps people get things from different cities, even different countries, with ease. “I like eating duck neck very much and I often buy it on Taobao from shops in Wuhan. It's much more delicious than what our local (当地的) stores sell, but cheaper,” said Zang Xin, a girl in Yangzhou.
While enjoying online shopping, many people also have worries, especially for middle school student buyers. Young students are easily attracted by advertisements on the Internet and buy things they don't need.
    “Middle school students should pay more attention to their study. Searching for things wastes their time,” said Jing Chunling, an education expert. “Besides, online shop owners have no idea of the ages of their buyers. Anyone can easily buy things that they want to. Some of goods are even bad for young students such as cigarettes and wine.”