( )是指在一定时期内和一定价格水平上，全社会对产品和服务的总购买力或总支付能力。

颈椎病颈椎牵引的角度，错误的是（）

A.颈椎前倾角度小时，牵引力作用于上颈椎

B.随颈椎前倾角度的加大，作用力的位置下移

C.颈椎前倾10°～20°较合适，以15～40分钟为宜

D.前倾一小角度，牵引力与颈椎的横截面垂直，减轻颈肩部疼痛

E.前倾10°～20°的牵引力，使扭曲于横突孔中的椎动脉得以伸展

我国各民族分布特点是______、_________，这为民族相互交往、团结合作、共同繁荣提供了有利条件。

TG的临界范围是 （）

A.1.69～2.25mmol／L

B.5.20～5.66mmol／L

C.6.20～6.66mmol／L

D.7.20～7.66mmol／L

E.8.0mmol/L

Agricultural experts met in Ethiopia last week to discuss ways to help sub-Saharan Africa become a major producer of wheat. The area traditionally produced little wheat, while North Africa was the grain basket.

Wheat production fell sharply in sub-Saharan countries during the 1980s. In the 1960s, attempts were made to grow wheat in sub-Saharan Africa, including South Africa and Zimbabwe. But those countries found it was less costly to import wheat from Europe and the United States. Another problem is that Africa's wheat farms were often far from population centers. There also were transportation issues. And some lowlands were not a good place to grow wheat.

Hans Joachim Braun_,one of the experts, says now is a good time to increase wheat production. In the last four years we have seen three major price hikes, where the wheat price and other staple process (主食加工）exploded. And that puts a big, big bill on countries which are depending on wheat imports, and Africa is the biggest wheat importer.

He also says demand for wheat in sub-Saharan Africa is growing faster than for any other crop. With higher income people would like to have more diversified(多样化）food. But that is possible not the most important one. The most important one is that there is a tremendous migration(移民）of in particular male labor to the cities. And wheat products are convenient food because you can easily buy it. It's easy to process and you also can store it for a few days, which is different from some of the maize and rice products.

There are three possible challenges for growing more wheat in Africa： climate change, disease and pests, like insects. Mr. Braun says rising temperatures should not have a major effect on wheat. In fact, he says, it could help wheat grow in areas with high rainfall totals. As for fighting disease and pests, experts suggest growing more resistant crops. In addition, railroads and roads would have to be improved so large amounts of wheat could be moved to large markets.

小题1:What does the word "hikes" in Paragraph 3 probably refer to?

A．big changes

B．large increases

C．long trips

D．big bills小题2:Wheat price exploding indicates_____.

A．sub-Saharan countries need to increase wheat production badly

B．sub-Saharan countries have to issue more money

C．sub-Saharan countries should grow more Corn

D．importing much wheat is urgent小题3:Why is there a higher demand for wheat in sub-Saharan Africa？

A．Because the number ofhungry people there is increasing.

B．Because higher income people have the diversified need of food.

C．Because male labor are crowding into the cities.

D．Because the wheat price is lower.小题4:According to Mr. Braun the main challenges for growing more wheat in Africa are_____.

A．climate change and disease

B．resistant crops and climate change

C．rising temperatures and disease and pests

D．disease and pests and inconvenient transportation

要删除当前数据表文件的“性别”字段，应当使用命令（）。

A.MODIFY STRUCTURE

B.DELETE 性别

C.REPLACE 性别 WITH ""

D.ZAP