下列属于单方面资本转移的项目是( )。 A．华侨汇款 B．政府对外援助捐赠 C．对

下列叙述中正确的是 [ ]

A．向含有CaCO₃沉淀的水中通入CO₂至沉淀恰好溶解，再向溶液中加入NaHCO₃饱和溶液，又有CaCO₃沉淀生成

B．向Na₂CO₃溶液中逐滴加入等物质的量的稀盐酸，生成的CO₂与原Na₂CO₃的物质的量之比为1:2

C．等质量的NaHCO₃和Na₂CO₃分别与足量盐酸反应，在同温同压下，生成的CO₂体积相同

D．向Na₂CO₃饱和溶液中通入CO₂，有NaHCO₃结晶析出

2010年5月1日至20日的20天里，每天参观上海世博会的人数统计如下：（单位：万人次）

20，22，13，15，11，11，14，20，14，16

18，18，22，24，34，24，24，26，29，30

（1）写出以上20个数据的众数、中位数、平均数；

（2）若按照前20天参观人数的平均数计算，估计上海世博会期间（2010年5月1日至2010年10月31日）参观的总人数约是多少万人次？

（3）要达到组委会预计的参观上海世博会的总人数约为7000万人次，2010年5月21日至2010年10月31日期间，平均每天参观人数约为多少万人次？（结果精确到0.01万人次）

在某一确定材料中温度波的频率越高，则温度波的振幅沿传播方向衰减（）

A、越快

B、越慢

C、不变

D、视情况而定

小玉家开办了一个养鸡场，在孵化雏鸡的过程中往往因温度过高而使雏鸡的成活率降低，请你用学过的知识帮他设计一个装置，当温度过高时自动报警．

阅读理解。

      The nervous-looking (紧张不安地) young man had waited for a few moments outside the jeweler's shop

before he got enough courage (勇气) to enter. He was warmly greeted by a young assistant. James felt a rush

blood to his face as he explained he would bring in his future wife to choose a birthday present. The assistant

listened carefully and told him he'd better buy a necklace. He wasn't used to buying jewelry and was a little

worried about overspending. After some discussion as to reasonable price and type, the assistant showed him

dozens of necklaces and helped him to choose. At last James chose one and left the shop promising to return

at five o'clock. When, half an hour later, James did return to the shop with his future wife, Laura, the assistant

acted as if she had never seen him before. When she was asked to show them some necklaces, she first

brought out some inexpensive ones for them to choose and then gave them the one she had prepared. A choice

was soon made and they went away, satisfied. James would certainly come back to buy what he wanted when

he got married.

1. A good title for this passage is _____. [ ]

A. A Clever Assistant

B. Buying a Birthday Present

C. How to Choose a Necklace

D. A Brave Young Man

2. The word "overspending" in this passage means _____. [ ]

A. spending too much money

B. spending too much time

C. spending more time than be planned

D. spending too much time and too much money

3. When James told the assistant why he wanted to buy a present, his face _____. [ ]

A. turned pale　　　

B. turned red

C. turned yellow　　　

D. turned black

4. James would come back to buy what he wanted because _____. [ ]

A. the assistant knew how to satisfy the people who came to buy things

B. the necklace was good

C. Laura liked the necklace

D. the assistant who served James was very beautiful