填空题

对飞机的飞行速度进行15次独立试验,测得飞机的最大飞行速度(单位:m/s)如下: 422.2 418.7 425.6 420.3 425.8 423.1 431.5 428.2 438.3 434.0 41 2.3 417.2 413.5 441.3 423.7 根据长期经验,可以认为最大飞行速度服从正态分布,试求最大飞行速度期望值的置信区间.(置信度为95%)()

答案: (420.35 429.74)
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单项选择题

根据下列文章,请回答 23~30 题。
The Drink Your Body Needs Most
1 0UF bodies are estimated to be about 60 to 70%water. Blood is mostly water. and our muscles,lungs,and brain all contain a lot of water. Water is needed to regulate body temperature and to provide the means for nutrients(滋养物)to travel to all our organs. Water also transports oxygen to our cells,removes waste,and protects our joints and Organs.
2 We lose water through urination(排尿),respiration(呼吸),and by sweating. If you are very active you lose more water than if you do not take much exercise. Symptoms of mild dehydration(脱水)include chronic pains in joints and muscles,lower back pain,headaches,and constipation(便秘)。A strong smell to your urine,along with a yellow color indicates that you are not geeing enough water. Thirst is an obvious sign of dehydration and in fact. You need water long before you feel thirsty.
3 A good rule of thumb(好的做法)is to take your body weight in pounds and divide that number in half. That gives you the number of ounces(盎司)of water per day that you need. For example,if you weigh 160 pounds,you should drink at least 80 0unces of water per day.1f you exercise you should drink another 8-ounce glass of water for every 20 minutes you are active. If you drink coffee or alcoh01.you should add at Least an equal amount of water. When you are traveling on an airplane it is good to have 8 0unces of water for every hour you are on board the plane.
4 It may be difficult to drink enough water on a busy day. Be sure you have water handy at all times by keeping a bottle for water with you when you are workin9,traveling,or exercisin9.If you get bored with plain water,add a bit of lemon for a touch of flavor. There are some brands of flavored water available. but some of them have sugar or artificial sweeteners that you don't need.
第 23 题 Paragraph 1____________

A.1f
B.you
C.If
单项选择题

根据下列文章,请回答 36~40 题。
Smart Exercise
Doctors are starting to find more and more information that suggests a connection between exercise and brain development.Judy Cameron。a scientist at Oregon Health and Science University, studies brain development.According to her research,it seems that exercise can make blood vessels,including those in the brain,stronger and more fully developed.Dr.Cameron claims this allows people who exercise to concentrate better.As she says:“While we already know that exercise is good for the heat exercise can literally cause physical changes in the brain
The effects of exercise on brain development can even be seer in babies.Babies who do activities that require a lot of movement and physical activity show greater brain development than babies who are less physically active.With babies,even a little movement can show big results.Margaret Barnes,a pediatrician(儿科医师),believes in the importance Of exercise.She thinks that many learning disabilities that children have in elementary school or high school can be traced back to a lack of movement as babies.“Babies need movement that stimulates their five senses.They need to establish。connection between motion and memory.In this way, as they get older, children will begin;to associate physical activity with higher learning,”says Margaret.
Older people can beef up their brains as well.Cornell University studied a group of seniors ranging in age from seventy to seventy-nine.Their study showed a short-term memory increase of up t0 40 percent after exercising just three hours a week the exercise does not have to be very difficult.but it does have to increase the heart rate Als0。just like the motion for infants,exercise for older people should involve some complexity.Learning some new skills or motions helps to open up memory paths in the brain that may not have been used for a long time.
For most people。any type of physical activity that increases the heart rate is helpful.The main goal is to increase the brain’s flow of blood.And your brain can benefit from as little as two to three hours of exercise a week.
第 36 题 Research by Dr Cameron seems to suggest that exercise can
A.generate new blood vessels.
B.change the way a person thinks.
C.promote brain development.
D.divert one’s attention.

A.Judy
B.According
C.Dr.Cameron
D.As
E.Babies
F.With
G.Margaret
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Older
M.Cornell
N.Their
O.but
P.Learning
Q.
For
R.The
S.And
T.generate
U.
B.change
V.
C.promote
W.
D.divert
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