Across the Deserts

　　The SaharaDesertis the largest desert in the world. It stretches across Africa fromSenegaltoEgypt. TheSaharaDesertis an unfriendly environment. During the day it"s very hot, and at night it’s sometimes very cold. It is also difficult to find water in theSahara.

　　In 2006, Kevin Lin, Ray Zahab, and Charlie Engle decided to do something very difficult. They made the decision to run across the Sahara Desert 4,300 miles (6,920km). It seemed impossible to do, but they wanted to try. The three men liked to test themselves, and this would be a very big test.

　　On the morning of November 2, Kevin, Ray, and Charlie started their trip across theSahara. Every morning they began running at 5:00. At11 a.m. they stopped and rested until 5 p.m. Then they ran again until 9:30 in the evening. Each day they ran about 40 miles (64 km). Every day it was the same thing. They got up and ran. They listened to music on their iPods, and they ran and ran.

　　Kevin, Ray, and Charlie needed to eat a lot of food during their trip. Most people need about 2,000 calories of food each day. Kevin, Ray, and Charlie needed between 6,000 and 9,000 calories every day. That"s a lot of food! They also needed to drink a lot of water.

　　The three men had some problems on their trip, and many times they wanted to quit and go home. It was often very hot (140°F/60°C) during the day, and the heat made them sick. Their legs and feet hurt. Sometimes it was very windy, and they couldn"t see. One time they got lost. But they didn"t quit. After 111 days, Kevin, Ray; and Charlie successfully finished their trip across theSaharaDesert. They hugged each other and put their hands in the water of theRed Sea. Then they ran to a hotel to take a long shower.

　　词汇：

　　Stretch / strɛtʃ / v. 延伸，伸展

　　Calorie / "kælərɪ / n. 卡(路里)，小卡，大卡

　　Quit / kwɪt / v. 停止，放

　　注释：

Each day the men ran for approximately eight hours.

A:Right B:Wrong C:mentioned

Across the Deserts

　　The SaharaDesertis the largest desert in the world. It stretches across Africa fromSenegaltoEgypt. TheSaharaDesertis an unfriendly environment. During the day it"s very hot, and at night it’s sometimes very cold. It is also difficult to find water in theSahara.

　　In 2006, Kevin Lin, Ray Zahab, and Charlie Engle decided to do something very difficult. They made the decision to run across the Sahara Desert 4,300 miles (6,920km). It seemed impossible to do, but they wanted to try. The three men liked to test themselves, and this would be a very big test.

　　On the morning of November 2, Kevin, Ray, and Charlie started their trip across theSahara. Every morning they began running at 5:00. At11 a.m. they stopped and rested until 5 p.m. Then they ran again until 9:30 in the evening. Each day they ran about 40 miles (64 km). Every day it was the same thing. They got up and ran. They listened to music on their iPods, and they ran and ran.

　　Kevin, Ray, and Charlie needed to eat a lot of food during their trip. Most people need about 2,000 calories of food each day. Kevin, Ray, and Charlie needed between 6,000 and 9,000 calories every day. That"s a lot of food! They also needed to drink a lot of water.

　　The three men had some problems on their trip, and many times they wanted to quit and go home. It was often very hot (140°F/60°C) during the day, and the heat made them sick. Their legs and feet hurt. Sometimes it was very windy, and they couldn"t see. One time they got lost. But they didn"t quit. After 111 days, Kevin, Ray; and Charlie successfully finished their trip across theSaharaDesert. They hugged each other and put their hands in the water of theRed Sea. Then they ran to a hotel to take a long shower.

　　词汇：

　　Stretch / strɛtʃ / v. 延伸，伸展

　　Calorie / "kælərɪ / n. 卡(路里)，小卡，大卡

　　Quit / kwɪt / v. 停止，放

　　注释：

In the middle of the day: the men usually stopped running.

A:Right B:Wrong C:mentioned

Across the Deserts

　　The SaharaDesertis the largest desert in the world. It stretches across Africa fromSenegaltoEgypt. TheSaharaDesertis an unfriendly environment. During the day it"s very hot, and at night it’s sometimes very cold. It is also difficult to find water in theSahara.

　　In 2006, Kevin Lin, Ray Zahab, and Charlie Engle decided to do something very difficult. They made the decision to run across the Sahara Desert 4,300 miles (6,920km). It seemed impossible to do, but they wanted to try. The three men liked to test themselves, and this would be a very big test.

　　On the morning of November 2, Kevin, Ray, and Charlie started their trip across theSahara. Every morning they began running at 5:00. At11 a.m. they stopped and rested until 5 p.m. Then they ran again until 9:30 in the evening. Each day they ran about 40 miles (64 km). Every day it was the same thing. They got up and ran. They listened to music on their iPods, and they ran and ran.

　　Kevin, Ray, and Charlie needed to eat a lot of food during their trip. Most people need about 2,000 calories of food each day. Kevin, Ray, and Charlie needed between 6,000 and 9,000 calories every day. That"s a lot of food! They also needed to drink a lot of water.

　　The three men had some problems on their trip, and many times they wanted to quit and go home. It was often very hot (140°F/60°C) during the day, and the heat made them sick. Their legs and feet hurt. Sometimes it was very windy, and they couldn"t see. One time they got lost. But they didn"t quit. After 111 days, Kevin, Ray; and Charlie successfully finished their trip across theSaharaDesert. They hugged each other and put their hands in the water of theRed Sea. Then they ran to a hotel to take a long shower.

　　词汇：

　　Stretch / strɛtʃ / v. 延伸，伸展

　　Calorie / "kælərɪ / n. 卡(路里)，小卡，大卡

　　Quit / kwɪt / v. 停止，放

　　注释：

They sometimes felt sick because it was so hot.

A:Right B:Wrong C:mentioned

Across the Deserts

　　The SaharaDesertis the largest desert in the world. It stretches across Africa fromSenegaltoEgypt. TheSaharaDesertis an unfriendly environment. During the day it"s very hot, and at night it’s sometimes very cold. It is also difficult to find water in theSahara.

　　In 2006, Kevin Lin, Ray Zahab, and Charlie Engle decided to do something very difficult. They made the decision to run across the Sahara Desert 4,300 miles (6,920km). It seemed impossible to do, but they wanted to try. The three men liked to test themselves, and this would be a very big test.

　　On the morning of November 2, Kevin, Ray, and Charlie started their trip across theSahara. Every morning they began running at 5:00. At11 a.m. they stopped and rested until 5 p.m. Then they ran again until 9:30 in the evening. Each day they ran about 40 miles (64 km). Every day it was the same thing. They got up and ran. They listened to music on their iPods, and they ran and ran.

　　Kevin, Ray, and Charlie needed to eat a lot of food during their trip. Most people need about 2,000 calories of food each day. Kevin, Ray, and Charlie needed between 6,000 and 9,000 calories every day. That"s a lot of food! They also needed to drink a lot of water.

　　The three men had some problems on their trip, and many times they wanted to quit and go home. It was often very hot (140°F/60°C) during the day, and the heat made them sick. Their legs and feet hurt. Sometimes it was very windy, and they couldn"t see. One time they got lost. But they didn"t quit. After 111 days, Kevin, Ray; and Charlie successfully finished their trip across theSaharaDesert. They hugged each other and put their hands in the water of theRed Sea. Then they ran to a hotel to take a long shower.

　　词汇：

　　Stretch / strɛtʃ / v. 延伸，伸展

　　Calorie / "kælərɪ / n. 卡(路里)，小卡，大卡

　　Quit / kwɪt / v. 停止，放

　　注释：

Sometimes they couldn"t see the road because it was windy.

A:Right B:Wrong C:mentioned

Across the Deserts

　　The SaharaDesertis the largest desert in the world. It stretches across Africa fromSenegaltoEgypt. TheSaharaDesertis an unfriendly environment. During the day it"s very hot, and at night it’s sometimes very cold. It is also difficult to find water in theSahara.

　　In 2006, Kevin Lin, Ray Zahab, and Charlie Engle decided to do something very difficult. They made the decision to run across the Sahara Desert 4,300 miles (6,920km). It seemed impossible to do, but they wanted to try. The three men liked to test themselves, and this would be a very big test.

　　On the morning of November 2, Kevin, Ray, and Charlie started their trip across theSahara. Every morning they began running at 5:00. At11 a.m. they stopped and rested until 5 p.m. Then they ran again until 9:30 in the evening. Each day they ran about 40 miles (64 km). Every day it was the same thing. They got up and ran. They listened to music on their iPods, and they ran and ran.

　　Kevin, Ray, and Charlie needed to eat a lot of food during their trip. Most people need about 2,000 calories of food each day. Kevin, Ray, and Charlie needed between 6,000 and 9,000 calories every day. That"s a lot of food! They also needed to drink a lot of water.

　　The three men had some problems on their trip, and many times they wanted to quit and go home. It was often very hot (140°F/60°C) during the day, and the heat made them sick. Their legs and feet hurt. Sometimes it was very windy, and they couldn"t see. One time they got lost. But they didn"t quit. After 111 days, Kevin, Ray; and Charlie successfully finished their trip across theSaharaDesert. They hugged each other and put their hands in the water of theRed Sea. Then they ran to a hotel to take a long shower.

　　词汇：

　　Stretch / strɛtʃ / v. 延伸，伸展

　　Calorie / "kælərɪ / n. 卡(路里)，小卡，大卡

　　Quit / kwɪt / v. 停止，放

　　注释：

On their trip across the desert: the three men ran through five countries.

A:Right B:Wrong C:mentioned

含尘气体通过降尘室的时间是t，最小固体颗粒的沉降时间是t0，为使固体颗粒都能沉降下来，必须（）

A:t B:t＝t0 C:t>t0

80C51单片机时钟周期为T0，则机器周期为（）。

A:2T0 B:4T0 C:8T0 D:12T0

若f（t）<----->F（s），Re[s]>s0，且有实常数t0>0，则（）

A:f（t-t0）e（t-t0）<----->e^-st0F（s） B:f（t-t0）e（t-t0）<----->e^-st0F（s），Re[s]>s0 C:f（t-t0）e（t-t0）<----->e^st0F（s），Re[s]>s0 D:f（t-t0）e（t-t0）<----->e^-st0F（s），Re[s]>0

已知f（t），为求f（t0-at）则下列运算正确的是（其中t0，a为正数）（）

A:f（-at）左移t0 B:f（-at）右移 C:f（at）左移t0 D:f（at）右移

用t0和t1表示产生1.0密度值的无屏和有屏照射量，则增感率的表达式是（）

A:f=t0/t1 B:f=t1/t0 C:f=t0-t1 D:f=t1-t0 E:f=t0+t1