问题 选择题

若一次函数y=ax+b(a≠0)的图象与x轴的交点坐标为(-2,0),则抛物线y=ax2+bx的对称轴为(   )

A.直线x=1

B.直线x=-2

C.直线x=-1

D.直线x=-4

答案

C.

题目分析:∵一次函数y=ax+b(a≠0)的图象与x轴的交点坐标为(-2,0),

∴-2a+b=0,即b=2a,

∴抛物线y=ax2+bx的对称轴为直线x=-

故选C.

填空题
阅读理解

What do you use to get around town? A car? A bike? Your feet ? perhaps you should try a segway!

The Segway is perfect for short journeys. It’s an electric vehicle that consists of a platform between two wheels, with a pole that connects the platform to the handlebars. To ride it , you step up onto the platform, and control the Segway by moving your body. Lean forwards to go faster, and back-wards to slow down.

On older models, direction was controlled by a twist grip(扭转把手)on the left handlebar. This varies the speeds between the two motors, and a decrease in the speed of the left wheel would turn the Segway to the left . With newer models you simply lean to the left or right. Meanwhile, a gyroscope (陀螺仪)detects your movements and prevents the machine from falling over. The Segway has a maximum speed of 19 km per hour and a range of about 38 km. after that, you need to plug it and recharge the battery.

Segways are used for a variety of purposes. People with mobility problems can now enjoy walks in the country with their friends and family. Some golfers see them as an alternative to the golf cart . And dog owners now have an easier way to take the dog to the park. A few police forces use Segways, too. They allow officers to move quickly while maintaining contact with the public. They’re also becoming a common sight on airport . However, the most popular use is in tourism , particularly for city tours . Visit any major tourist city in summer, sit outside a cafe for a while and there’s a good chance you’ll see a group of tourists passing on Segways.

小题1:How do you turn to the left on a Segway of the new model?

A.Lean to the left

B.Adjust the twist grip

C.Press the left bar

D.Control the gyroscope小题2:How far can you travel on a Segway at most?

A.Less than 19 km

B.About 19 km

C.About 38 km

D.Over 45 km小题3:The Segway is most commonly used by       .

A.families

B.golfers

C.police

D.tourists小题4:Which of the following correctly shows the order in which information about the Segway is provided?

A.Introduction→Ways of application→ structure→Principle of operation

B.Introduction→ Principle of operation→Structure →Ways of application

C.Introduction → Structure → Principle of operation →ways of application

D.Structure→ Introduction→Principle of operation→Ways of application小题5:Which of the following pictures shows the Segways being used?