302.　 已知：正三棱柱ABC-A′B′C′中，AB′⊥BC′，BC＝2，求：线段AB′在侧面上的射影长.

解析： 如图，取BC的中点D.∵AD⊥BC，侧面⊥底面ABC，∴AD⊥侧面是斜线AB′在侧面的射影.又∵AB′⊥BC′，∴⊥BC′.

设BB′＝x，在RtΔ中，BE∶BD＝，＝.

∵E是ΔBB′C的重心.∴BE＝BC′＝

∴x＝·，解得：x＝.

∴线段AB′在侧面的射影长为.

301.　 正三棱柱ABC-A₁B₁C₁的侧面三条对角线AB₁、BC₁、CA₁中，AB₁⊥BC₁.求证：AB₁⊥CA₁.

解析：方法1　 如图，延长B₁C₁到D，使C₁D＝B₁C₁.连CD、A₁D.因AB₁⊥BC₁，故AB₁⊥CD；又B₁C₁＝A₁C₁＝C₁D，故∠B₁A₁D＝90°，于是DA₁⊥平面AA₁B₁B.故AB₁⊥平面A₁CD，因此AB₁⊥A₁C.

方法2　 如图，取A₁B₁、AB的中点D₁、P.连CP、C₁D₁、A₁P、D₁B，易证C₁D₁⊥平面AA₁B₁B.由三垂线定理可得AB₁⊥BD₁，从而AB₁⊥A₁D.再由三垂线定理的逆定理即得AB₁⊥A₁C.

说明　 证明本题的关键是作辅助面和辅助线，证明线面垂直常采用下列方法：

(1)利用线面垂直的定义；

(2)证明直线垂直于平面内的两条相交直线；

(3)证明直线平行于平面的垂线；

(4)证明直线垂直于与这平面平行的另一平面.

　话题作文要有所创新，就应调用多种叙述方法。除以上叙事方式外，还可把文章分为时间顺序、空间顺序、逻辑顺序和意识流顺序。但无论使用何种叙述方法，其主要目的在于叙事条理清楚、层次分明。能将所选用的材料连缀成一个有机统一的整体。

例文1

童 年

　沙丁鱼罐头似的公共汽车在晒得发烫的柏油路上缓慢地爬着。我--瘦瘦小小的个子在拥挤着的人群中喘不过气来。“还要多久呀？”人们烦躁而沉闷的气氛充斥着整个车厢。忽然，我看见一位西装人士，正悄悄地把手伸入一位老人的口袋。我的第一反应就是有小偷！于是大声呼喊，一车人都回头惊悸地看着我，西装人士也恶狠狠地盯着我，随即又混入人群。我红着脸，还没到站就匆匆逃离了。仿佛那个小偷是我，我错了吗？年幼的我不懂那么多，只知道那是我心灵的选择。

　我的大学

　毕业考试了，我坐在考场上为未来而努力。其实，我稍稍瞥一眼就可看见邻桌的试卷，恰巧我有一题忘了。怎么办？看还是不看？我在矛盾的边缘游移。看了，也许就意味着我会有一份好工作，一个美好的前途，一个美好幸福的家庭……那就看吧！不行！我的心灵叩问着我：那是你吗？那是诚实的你吗？你不能为此失去诚实的品德呀！

　可是，如果我不看，我可能就会与“成功”失之交臂，我也许将过着贫困潦倒的生活。但是，我如果那样做，我就不是忠于自我，即使我有光明的前途又怎样？

84. Why will people with musical training find it easier to learn Chinese, according to the researchers? (No more than 15 words.)

__________________________________________________________________________________

SECTION C

Directions: Write an English composition according to the instructions given below.

Write a composition of about 120 words according to the information below:

83. What does the underlined “work the other way round” mean in the last paragraph? (No more than 12 words.)

__________________________________________________________________________________

82. How did the non-Chinese with no musical background react to the audiotape? (No more than 6 words.)

__________________________________________________________________________________

SECTION B

Directions: Read the following passage. Answer the questions according to the information given in the passage and the required words limit. Write your answers on your answer sheet.

Anyone who has tried to learn Chinese can prove how hard it is to master the pitch (音调) required to speak and understand it. And anyone who has tried to learn to play the violin or other instruments can report similar challenges.

Now researchers have found that people with musical training have an easier time learning Chinese.

Writing in the online edition of Nature Neuroscience, researchers from Northwestern University say that both skills use parts of the brain that help people notice changes in pitch.

One of the study’s authors, Nina Kraus, said the findings suggested that studying music “actually tunes our sensory (感官的) system.” This means that schools that want children to do well in languages should hesitate before cutting music programs, Dr. Kraus said. She said music training might also help children with language problems.

Chinese speakers have been shown to have a more complex programming of pitch patterns in their brains than English speakers do. This is most probably because in Chinese and other Asian languages, pitch plays a central role. A single word can have several meanings depending on how it is pronounced.

For this study, the researchers looked at 20 non-Chinese speaking volunteers, half with no musical background and half who had studied an instrument for at least six years.

As they were shown a movie, the volunteers also heard an audiotape of the Chinese word “mi” in three of its meanings: squint (眯), bewilder (迷) and rice. The researchers recorded activity in their brain stems (脑干) to see how well they were processing the sounds.

Those with a music background showed much more brain activity in response to the Chinese sounds.

The lead author of the study, Patrick C. M. Wong, said it might work the other way round. It appears that native speakers of tonal (音调的) languages may do better at learning instruments, Dr. Wong said.

81. Why is the arrangement of pitch patterns in Chinese speakers’ brains more complex? (No more than 8 words.)

__________________________________________________________________________________

What they do with a computer: ◆Girls prefer to use computers for _ 76　 .

◆Boys prefer to use computers for 　77　 　and understanding

information.

How they feel about a computer: ◆Girls are afraid of breaking it.

　　　　　　　　　　　　　 ◆Boys are 　78　 　such worry.

Their 　79　 　to computer games: ◆Girls think they are boring because the characters are irrelevant

to their lives.

◆Boys don’t have such feelings.

Before high school: ◆Girls use computers 　71　 　boys.

In high school: ◆Girls make up 　72　 　in computer science classes.

　　　　　　 ◆Girls feel less comfortable with the computer.

　　　　　　 ◆Boys use computers 　73　 　often than girls after class.

　　　　　　 ◆Boys feel more 　74　 　when using computers.

70. If Bob, chairman of a book club, wants to learn to use the computer to help manage his book club, which of the following numbers will he probably call?

　 A. 512-743-8905　　 B. 512-743-8908 　　C. 931-7620　　 D. 931-7623

PART FOUR WRITING

SECTION A

Directions: Read the following passage. Complete the diagram / Fill in the numbered blanks by using the information for the passage.

　Write NO MORE THAN 3 WORDS for each answer

The girls in this sixth grade class in East Palo Alto, California, all have the same access to computers as boys. But researchers say, by the time they get to high school, they are victims of what the researchers call a major new gender (性别) gap in technology. Janice Weinman of the American Association of University Women (AAUW) says, "Girls tend to be less comfortable than boys with the computer. They use it more for word processing rather than for problem solving, rather than to discover new ways in which to understand information.

　 After re-examining a thousand studies, the AAUW researchers found that girls make up only a small percentage of students in computer science classes. Girls rate themselves significantly lower than boys in their ability and confidence in using computers. And they use computers less often than boys outside the classroom.

　 An instructor of a computer lab says he's already noticed some difference. Charles Cheadle of Cesar Chavez School says, "Boys are not so afraid they might do something that will harm the computer, whereas girls are afraid they might break it somehow."

　　 Six years ago, the software company Purple Moon noticed that girls' computer usage was falling behind boys. Karen Gould with the company says, "The number one reason girls told us they don't like computer games is not that they're too violent, or too competitive. Girls just said they're unbelievably boring." What girls want, Purple Moon found, is characters they can relate to and story lines relative to what's going on in their own lives. "What we definitely found from girls is that there is no intrinsic (内在的) reason why they wouldn't want to play on a computer; it was just a content thing," says Karen Gould.

　 The sponsor of the study says it all boils down to this: the technology gender gap that separates the girls from the boys must be closed if women are to compete effectively with men in the 21st century.

What has caused the new gender gap in technology?