饲养金鱼时，还可以在鱼缸中加适量水草和河泥，这样的鱼缸可以看作一个（ ）
A．生物圈
B．生态系统
C．食物链
D．食物网
生态系统是在一定的空间范围内，生物与环境形成的统一整体．它是由生物部分和非生物部分组成，鱼缸里的水草属于生产者，金鱼属于消费者，河泥里有细菌和真菌属于分解者，非生物部分有阳光、空气、水等，因此，这样的鱼缸 可以看作是一个生态系统．
故选：B．
任务型读写（共10小题；每小题1分，满分10分） 阅读下面短文，根据所读内容在表格中的空白处填入恰当的单词。注意：每个空格只填一个单词。 People unhappy with the rich: Poll There is growing dissatisfaction toward rich people, according to a new online poll. The poll by the China Youth Daily in collaboration(与…合作) with Sina.com has highlighted the apparent discontent (不满)over the country's widening income gap. Nearly 8,000 people filled in online questionnaires last week, and when asked to use three words to describe society's rich, the top responses were "extravagant"(奢侈的), "greedy" and "corrupt". About 57 percent of those polled said that "extravagant" was the best word to describe the rich, followed closely by "greedy". Ironically, despite their dissatisfaction, 93 percent of those polled wished they could be rich too, and that richer people should be "socially responsible". Some 33 percent of respondents also praised rich people for being "smart". Nearly 90 percent of respondents agreed that most people in society, including themselves, were willing to speak up for the poor but were reluctant to take action and actually do something for them. The survey comes on the heels of a heated debate over comments made by renowned economist Mao Yushi, who said he was "speaking for the rich and working for the poor". A report released by the Asian Development Bank last Wednesday revealed that China's Gini coefficient - an indicator of the wealth divide - rose from 0.407 in 1993 to 0.473 in 2004. An earlier CASS report said that the richest 10 percent of Chinese families now own more than 40 percent of all private assets, while the poorest 10 percent share less than 2 percent of the total wealth. The country's income disparity(悬殊) is close to that of Latin America, the report which came out in January said.
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