68. We, students of the senior middle school, are old enough to be 　　　　(独立自主) of our parents.　

67. To become a politician a sound knowledge on how to 　　　　(交流) is essential. 　

66. Don’t leave the lights on -- It wastes 　　　　(电流).　

5. chew　 A. drew　 B. nephew　 C. reward　 D. review

第二节 补全对话 (共5小题；每小题1分，满分5分)

根据对话内容，从对话后的选项中选出能填入空白处的最佳选项，并在答题卡上将该项涂黑。选项中有两项为多余选项。

-- For years some people have been saying that railways are dead. They say, “Trains are slow, and they lose money. Motorcars and planes have made them unnecessary.”

-- 　61　 　I think in these days of expensive oil, railways have become highly competitive with motorcars and planes.

-- Right. If you want to carry people or goods from place to place, they are much cheaper than planes.

-- 　62　 　A plane goes in a straight line, and so does a railway.

-- What is more, it takes you from the heart of a city into the heart of another. 　63　 　Nor does it hold you up as a car does in heavy traffic.

-- 　64　 　Modern railway lines give you a smooth, untroubled journey. We`ve just entered the age of super-fast trains, traveling at 160 miles an hour and more.

-- 　65　 　

A. So railways will have very bright future, I dare say.

B. It doesn’t leave you as a plane does, miles and miles from the city center.

C. Far from being dead, railways are developing very quickly.

D. Trains are really slower than planes.

E. And they have much in common with planes.

F. But it is far from the truth.

G. Trains are really more comfortable than planes.

第三节 　单词拼写(10小题，每小题1分；满分10分)

　　 根据下列句子及所给汉语注释，在答题卡上相应题号的横线上写出空缺处各单词的正确形式。(每空只写一词)

4. gentle　 A. cigar　 B. geography　 C. language　 D. high

3. moustache　 A. children　 B. technological　 C. attach　 D. chef

2. equip　 A. suitable　 B. quiet　 C. guide　 D. distinguish

1. certificate　 A. fade　 B. account　 C. capture　 D. voyage

5．

图2－2

　　 如图2－2，当电键S断开时，用光子能量为2.5 eV的一束光照射阴极P，发现电流表读数不为零．合上电键，调节滑动变阻器，发现当电压表读数小于0.60 V时，电流表读数仍不为零；当电压表读数大于或等于0.60 V时，电流表读数为零．

(1)求此时光电子的最大初动能的大小．

(2)求该阴极材料的逸出功．

解析：设用光子能量为2.5 eV的光照射时，光电子的最大初动能为E_km，阴极材料逸出功为W₀，

当反向电压达到U＝0.60 V以后，具有最大初动能的光电子也达不到阳极，因此eU＝E_km

由光电效应方程：E_km＝hν－W₀

由以上二式：E_km＝0.6 eV，W₀＝1.9 eV.

所以此时最大初动能为0.6 eV，该材料的逸出功为1.9 eV.

答案：0.6 eV　1.9 eV

4．紫光在真空中的波长为4.5×10^－7 m，问：

(1)紫光光子的能量是多少？

(2)用它照射极限频率为ν₀＝4.62×10¹⁴ Hz的金属钾能否产生光电效应？

(3)若能产生，则光电子的最大初动能为多少？(h＝6.63×10^－34 J·s)

解析：(1)E＝hν＝h＝4.42×10^－19 J

(2)ν＝＝6.67×10¹⁴ Hz，因为ν>ν₀，所以能产生光电效应．

(3)E_km＝hν－W₀＝h(ν－ν₀)＝1.36×10^－19 J.

答案：(1)4.42×10^－19 J　(2)能　(3)1.36×10^－19 J