题干

以下关于生态系统结构和功能的叙述,正确的是(  )

A:生态系统的结构包括生产者、消费者和分解者以及无机环境

B:物质循环是指碳、氢等元素在生物群落内循环往复,反复利用

C:生态系统都必须有能量输入,才能保持相对稳定的状态

D:因为生态系统具有自我调节能力,所以存在负反馈调节

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答案(点此获取答案解析)

C

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    Xiaomi's sales strategy is largely responsible for the decline, having grown indistinguishable from that of many other Chinese manufacturers, according to Hong Kong-based cell-phone market journalist Yasuhiro Yamane. When the company first arrived on the scene in 2011 and 2012, its products were sold online by reservation only, building an air of exclusivity(排外)and lending the brand a high image. This strengthened the appeal of the smart phones, which resembled Apple's iPhones.

    But starting in 2013, Xiaomi began concentrating on high-volume sales, allowing many more resellers to carry its phones—a critical turning point in the company's fortunes. While sales increased, Xiaomi's products became viewed less as premium items and more as widely available, mass-market phones, according to Yamane.

    To keep consumers from losing interest, Xiaomi introduced a lower-end brand, Redmi, in July 2013. Phones in that family sell for 1000 yuan($150) or less, around half the price of products from the flagship Mi series.

    When China's economy began to skid at the end of 2014, the company leaned harder on the Redmi brand to hold on to market share in the following year—a grave mistake. Though it had some effect, the strategy ultimately “drove home the image of Xiaomi as a low-cost phone maker,” Yamane said.

    This should serve as a warning to other makers in China, where companies tend to emerge and quickly disappear due to their focus on short-term gains over long-term planning. “There is still a chance that Xiaomi could right itself and regain its old appeal,” Yamane said.