22．红光透过双缝在墙上呈现明暗相间的条纹，若将其中一个缝封住，在墙上可以观察到

A．条纹形状与原来相同，但亮度减弱

B．仍有条纹，但形状与原来不同

C．一片红光

D． 光源的像

　　　 第II卷(非选择题　 共4题　 共72分)

　　　 31．(17分)如图所示，为测定木块与斜面之间的动摩擦因数，某同学让木块从斜面上端自静止起作匀加速下滑运动，如图所示，他使用的实验器材仅限于①倾角固定的斜面(倾角未知)②木块、③秒表、④米尺。

　　　 实验中应记录的数据是　　　　　　　　 ；

　　　 计算摩擦系数的公式是μ=　　　　　　　　 ；

　　　 为了减小测量的误差，可采用的办法是　　　　　　 。

20．两个分子相距较远时，可以忽略它们之间的分子力，若规定此时它们的分子势能为零，当分子间距离逐渐减小到不能再靠近的过程中

　　 A．分子势能逐渐减小，其值总是负的

　　 B．分子势能逐渐增大，其值总是正的

　　 C．分子势能先减小后增大，其值先为负后为正

　　 D．分子势能先增大后减小，其值先为正后为负

　　　 21．为了观察门外情况，有人在门上开一小圆孔，将一块圆柱形玻璃嵌入其中，圆柱体轴线与门面垂直，从圆柱底面中心看出去，可以看到的门外入射光线与轴线间的最大夹角称做视场角。已知该玻璃的折射率为n，圆柱体长为l，底面半径为r，则视场角是

　　　 A．arcsin　 B. arcsin　　

C. arcsin　 D. arcsin

18．如图所示，要使电阻R₁消耗的功率最大，应该把电阻R₂的阻值调节到

　　 A．R₂=R₁+r

　　 B．R₂=R₁-r

　　 C．R₂=r

　　 D．R₂=0

　　　 19．如图所示，A和B为两个相同的环形线圈，共轴并靠近放置，A环中通有如图所示交流电i，则

　　 A．从t₁到t₂时间内AB两线圈相吸

　　 B．从t₂到t₃时间内AB两线圈相斥

　　 C．t₁时刻两线圈间作用力为零

　　 D．t₂时刻两线圈间吸引力最大

16．一木块静置于光滑水平面上，一颗子弹沿水平方向飞来射入木块中。当子弹进入木块的深度达到最大值2.0cm时，木块沿水平面恰好移动距离1.0cm。在上述过程中系统损失的机械能与子弹损失的动能之比为

　　 A．1 : 2　　 B．1 : 3　　 C．2 : 3　　 D．3 : 2

　　　 17．图中是一个平行板电容器，其电容为C，带电量为Q，上极板带正电。现将一个试探电荷q由两极板间的A点移动到B点，如图所示。A、B两点间的距离为s，连线AB与极板间的夹角为30°，则电场力对试探电荷q所做的功等于

　　 A．　　 B．

　　 C．　　 D．

15．汽车在水平地面上转弯，地面对车的摩擦力已达到最大值。当汽车的速率加大到原来的二倍时，若使车在地面转弯时仍不打滑，汽车的转弯半径应

　　 A．增大到原来的二倍　　 B．减小到原来的一半

　　 C．增大到原来的四倍　　 D．减小到原来的四分之一

75. Which of the following statements isn’t Dr York Chow’s opinion?

A. Hong Kong is better at dealing with viral outbreaks than its neighbours.

B. Infectious diseases could happen in any country.

C. Other territories should ask Hong Kong for help because it has more experience.

74. When the final decision will be made mainly depends on ______.

A. the demand for live chickens　　　　　　　　　　　　 B. the views of the public

C. the advice from experts

D. the time when regional slaughtering houses will be finished

73. According to the passage, the best way to fight against bird flu is to ______.

A. separate poultry from humans　　　　　　　　　　　 B. set up a central slaughtering house

C. set up several regional slaughtering houses　　　 D. get avian flu vaccination

72. It can be inferred from the first paragraph that ______.

A. the government is planning to take strong action to fight against bird flu

B. an outbreak which happened near Hong Kong made people very frightened

C. anti-bird flu contingency measures will come into use next month

D. Dr York Chow will organize a meeting to discuss the contingency plan

71. What’s the best title for this passage?

A. A New Scientific Discovery: Black Holes

B. How Do Black Holes Come Into Being?

C. What Are Black Holes?

D. Travel Through A Black Hole

E

Anti-bird flu contingency (意外事故) measures, including a proposal to separate poultry from humans and a series of　traffic and logistics (后勤) measures will be discussed at the Legislative Council's Food Safety and Environmental Hygiene Panel meeting next month. Secretary for Health, Welfare and Food Dr York Chow says the contingency plan would come into force if an outbreak occurred near Hong Kong.

Speaking on a radio talk show this morning, Dr Chow said the separation of poultry from humans policy, which will be determined after a decision whether to set up a central slaughtering (屠宰) house or several regional ones,　would be based on the　demand for live chickens.

He pointed out that at present there　were 30,000 live chickens imported from the Mainland and 30,000 supplied locally. If this demand persisted, there　would be　no central slaughtering house or wholesale point that could handle such an amount and regional slaughtering houses　could　be the choice.

He added that building of regional slaughtering houses took time, but stressed the need to study the views of the public and the sector before a final decision　was made.

Regarding avian flu vaccination (种痘) for humans, Dr Chow said it　was still being developed.　He added that it may not be reliable in the case of an outbreak as records show vaccination can only offer 5% protection against a virus.

He said Hong Kong had more experience and expertise than neighbouring territories in the fight against viral outbreaks, and　was willing to offer them help.　He added　there　was no “boundary” for infectious diseases and close cooperation among different countries had to be maintained to fight against a possible outbreak.