问题
选择题
如图是生态系统中碳循环示意图，“→”表示碳的流动方向。下列说法正确的是
A．图中A是生产者，B、D、E是消费者，C是分解者
B．该生态系统的结构包括A、B、C、D、非生物的物质和能量
C．该生态系统中食物网可表示为：
D．E每增加1kg的体重，至少需要25kg的A
答案
答案：D
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如图是生态系统中碳循环示意图，“→”表示碳的流动方向。下列说法正确的是
A．图中A是生产者，B、D、E是消费者，C是分解者
B．该生态系统的结构包括A、B、C、D、非生物的物质和能量
C．该生态系统中食物网可表示为：
D．E每增加1kg的体重，至少需要25kg的A
答案：D
| Nine states and the District of Columbia are doing away with the sales tax on items such as clothes, shoes and even notebooks over the next few weeks, just in time for back-to- school shopping. Most of the promotions last only a few days, so shoppers will have to act quickly to get a tax break. The tax holidays, which have already expired in two other states, apply to small and large items. For example, the tax break applies to any school supply that costs $15 or less in New Mexico. In Massachusetts, it covers most retail purchases of $2,500 or less. Stores may offer additional savings because these events "give retailers an opportunity to have a sale on top of what the state is doing," says Verenda Smith, government affairs associate at the Federation of Tax Administrators. No industry-wide figures are available about how much consumers save annually from these tax breaks. But Texas estimates that shoppers will save $47.4 million in taxes this year, nearly a 3 percent increase from the previous year. Massachusetts says shoppers saved roughly $10 million in taxes during its 2005 event. States that cast aside these promotions when a slow economy pinched state budgets are now reviving them in hopes of stimulating local economies. Some states also believe the gain in consumer goodwill helps balance out the loss in tax revenue. In some cases, tax losses are minimal because serious shoppers don’t stop at clothes and books. "While states give up sales tax, they usually break even on sales-tax collection," says J. Craig Shearman, a vice-president at the National Retail Federation. Sophie Beckmann, a certified public accountant at A. G. Edwards in St. Louis, says she’ll avoid that temptation by making a list of necessities. On the Missouri resident’s shopping list: notebooks, pencils, glue and three or four outfits for her son, who is entering the fifth grade this month. She plans to pocket any tax savings. "When you start buying more and spending more just because of the savings, then you’re not doing yourself a favor," Beckmann says. |
The District of Columbia is most possibly the ______ .
A．capital of the nine states
B．tenth state in the examples
C．capital of the United States
D．regional name of these states