中间再热的参数选择，对机组有何影响？

我们规定：对于任意实数A，若存在数列{an}和实数x（x≠0），使得A=a1+a2x+a3x2+…+anxn-1，则称数A可以表示成x进制形式，简记为：A= . x\～(a1)(a2)(a3)…(an-1)(an) ．如：A= . 2\～(-1)(3)(-2)(1) ，则表示A是一个2进制形式的数，且A=-1+3×2+（-2）×22+1×23=5． （1）已知m=（1-2x）（1+3x2）（其中x≠0）），试将m表示成x进制的简记形式． （2）若数列{an}满足a1=2，ak+1= 1 1-ak ，k∈N*，bn= . 2\～(a1)(a2)(a3)…(a3n-2)(a3n-1)(a3n) （n∈N*）．求证：bn= 2 7 •8n- 2 7 ． （3）若常数t满足t≠0且t＞-1，dn= . t\～( C 1n )( C 2n )( C 3n )…( C n-1n )( C nn ) ，求 lim n→∞ dn dn+1 ．

要正确绘制现金流量图，必须把握好现金流量的三要素，即大小、方向、作用点。其中，作用点是指( )。

A．时间序列的起点

B．时间序列的终点

C．现金增量的发生点

D．现金发生的时间点

Part 2

Questions 9-18

·Read the following passage and answer questions 9-18.
1. From Dr. R. S. Scorer of Britain’s Imperial Collage of the Science comes the latest theory about the lighting flashes. Dr. Scorer believes the cause is haft failing through super cooled clouds. Ice particles bouncing off the falling hail acquire a positive charge and rise to the top of the cloud while the hail carries a negative charge to the bottom of the cloud.
2. According to Dr. Scorer, Benjamin Franklin first proved thunderclouds are charged with electricity. Later investigations showed that the tops of the clouds have a great positive charge and the bottoms have great negative charge.
3. When the charges became great enough to break the insulating properties of the air, lighting flashes carry the electricity within the cloud, or from cloud to cloud, or from cloud to earth. But the question remained: How do the charges develop within the cloud.
4. To seek the cause, Dr. Scorer and his colleagues at the college first duplicated thundercloud current in a liquid tank. They found the mixture takes place only in the tops of the clouds.
5. Next a study of thunderclouds over the North Atlantic showed that the lighting occurs only when the temperature around cloud is below freezing. Particles at the top of the clouds begin to freeze but those in the remainder of the cloud stay unfrozen although below freezing temperature. In the laboratory, S.E. Reynolds whirled a refrigerated rod through ice particles and found that the particles bounced offthe rod acquired a positive charge. This was a missing link. Without hail and super cooled clouds, he concluded, there could be no lighting.

Questions 9-13

·For questions 9-13, choose the best title for each paragraph from below.
·For each numbered paragraph (1-5), mark one letter (A-G) on the Answer Sheet.
·Do not mark any letter twice.
9. Paragraph 1:______

• A. How the lightning flashes come about.
  10. Paragraph 2:______
• B. To measure moisture, scientist did the experiment.
  11. Paragraph 3:______
• C. Two discoveries based on Dr. Scorer’s theory.
  12. Paragraph 4:______
• D. Significance of Benjamin Franklin’s discovery.
  13. Paragraph 5:______
• E. Experiments were done to find the cause of lightning.
• F. Dr. Scorer found the cause of lightning flashes.
• G. The continuing study of lightning flashes.

小明去商店买长度达上万米的铜丝，营业员不用刻度尺来量，他用秤称．于是小明买回了一卷铜丝，小明很想知道这些铜丝的长度到底是多少，请设计一个实验帮小明测出这些铜丝的长度，写出实验步骤及计算公式．（金属铜的密度为已知，用ρ_铜表示）

铁刷汤功效与作用