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 brainThe 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 canA．generate new blood vessels．B．change the way a person thinks．C．promote brain development．D．divert one’s attention．

未知题型 某厂生产一批金属材料，其抗弯强度服从正态分布，现从这批金属材料中随机地抽取11个测其抗弯强度，得数据(单位：kg)如下： 42．5 42．7 43．0 42．3 43．4 44．5 44．0 43．8 44．1 43．9 43．7 求：①平均抗弯强度的置信度为0．95的置信区间； ②抗弯强度方差的置信度为0．90的置信区间．

单项选择题 根据下列文章,请回答 16～22 题。 Mother Nature Shows Her Strength Tornadoes (龙卷风).and heavy thunderstorms moved across the Great Lakes arid into Trumbull County on Saturday evening. The storms were dramatic and dangerous. George Snyder was driving the fire truck down Route 88 when he first noticed that a funnel (漏斗状) cloud was behind him. 'I stopped the truck and watched the funnel cloud. It was about 100 feet off the ground and I saw it go up and down for a while. It was moving toward Bradley Road and then suddenly it disappeared,' Snyder said.Snyder only saw one of the funnel clouds that passed through northeastern Ohio on Saturday. In Trumbull County, a tornado turned trees onto their sides. Some trees fell onto houses and cars. Other trees fell into telephone and electrical wires as they went down.Amanda Symcheck was having a party when the storm began. '1 knew something was wrong,' she said. '1 saw the sky 9o green and pink (粉红色). Then it sounded like a train rushing toward the house. I started crying and told everyone to go to the basemen[ for protection.'The tornado caused a lot of damage to cars and houses in the area. It will take a long time and much money to repair everything. There was also serious water damage from the thunderstorms. The heavy rains and high wind caused the power to go out in many homes.The storms caused serious flooding in areas near the river. More than four inches of rain fell in parts of Trumbull County. The river was so high that the water ran into streets and houses. Many streets had to be closed to cars and trucks because of the high water. This made it difficult for fire trucks, police cars, and other rescue vehicles to help people who were in trouble.Many people who live near the river had to leave their homes for their own safety. Some people reported five feet of water in their homes. Local and state officials opened emergency shelters for the people who were evacuated (撤走). The Red Cross served meals to them.'This was a really intense storm,' said Snyder. 'People were afraid. Mother Nature can be fierce. We were lucky this time. No one was killed.' 第 16 题 The weather was nice in Trumbull County on Saturday evening.A．RightB．WrongC．Not mentioned