1．Falling objects are pulled down to the ground by             .
A．gravity     B．resistance  C．speed D．acceleration（加速度）
2．Why do people make parachutes(降落伞)?
A．To look pretty and colourful in the air.   B．To slow down the falling speed.
C．To push against the air in the sky.   D．To accelerate the falling movement.
3．Which did Galileo discover?
A．A heavy ball falls faster than a light ball.      B．A light ball falls faster than a heavy ball.
C．A light ball and a heavy ball fall at the same speed.
D．A light ball and a heavy ball fall at different speed.
4．Which of the following is NOT true according to the passage?
A．Heavy and light objects fall equally when they are different in size.
B．When air resistance equals gravity, objects fall at terminal speed.
C．Without air; all falling objects get faster and faster at the same rate.
D．Slippers（拖鞋） and boots （靴子）fall at the same speed because they have the same shape

1．Falling objects are pulled down to the ground by             .

        A．gravity        B．resistance C．speed         D．acceleration（加速度）

2．Why do people make parachutes(降落伞)?

         A．To look pretty and colourful in the air.       B．To slow down the falling speed.

         C．To push against the air in the sky.     D．To accelerate the falling movement.

3．Which did Galileo discover?

         A．A heavy ball falls faster than a light ball.  B．A light ball falls faster than a heavy ball.

         C．A light ball and a heavy ball fall at the same speed.

         D．A light ball and a heavy ball fall at different speed.

4．Which of the following is NOT true according to the passage?

        A．Heavy and light objects fall equally when they are different in size.

         B．When air resistance equals gravity, objects fall at terminal speed.

         C．Without air; all falling objects get faster and faster at the same rate.

         D．Slippers（拖鞋） and boots （靴子）fall at the same speed because they have the same shape

1．Falling objects are pulled down to the ground by             .

      A．gravity     B．resistance  C．speed D．acceleration（加速度）

2．Why do people make parachutes(降落伞)?

       A．To look pretty and colourful in the air.   B．To slow down the falling speed.

       C．To push against the air in the sky.   D．To accelerate the falling movement.

3．Which did Galileo discover?

       A．A heavy ball falls faster than a light ball.      B．A light ball falls faster than a heavy ball.

       C．A light ball and a heavy ball fall at the same speed.

       D．A light ball and a heavy ball fall at different speed.

4．Which of the following is NOT true according to the passage?

      A．Heavy and light objects fall equally when they are different in size.

       B．When air resistance equals gravity, objects fall at terminal speed.

       C．Without air; all falling objects get faster and faster at the same rate.

       D．Slippers（拖鞋） and boots （靴子）fall at the same speed because they have the same shape

In 1986, when Monty Reed was a member of the Army Rangers (黑鹰突击 队), he had an accident. "It was a night jump, and we were jumping low," he recalls. "We were training. Somebody got too close to my parachute (降落伞)."The parachute below blocked Reed’s air and his parachute failed to open. Reed crashed a hundred feet to the ground, breaking his back in five places.
The next morning, Reed could not move. "Doctors said it was likely that I would never walk again." Reed stared out of his hospital window, wondering what the future would be like. It was the saddest moment of his life. "The experts are telling me my body doesn’t work! What am I supposed to do?" he thought.
To distract (转移注意力) himself, he picked up a book: Robert Heinlein’s Starship Troopers. The science-fiction describes a set of man-made muscles that would allow people to carry 2,000 pounds. He thought that if he could build something like that, it might be able to lift him out of his wheelchair. So he began his project and finally succeeded in building a set of robot legs. Several years later, he made an amazing recovery and was able to get up and walk away from his wheelchair. He even jumped out of an airplane again to celebrate.
Reed wanted to do something for others with the second chance that life had given him. He has now perfected the robot legs that can get the injured, the elderly and the paralyzed (瘫痪的) out of their wheelchairs. Now he has started his own company to make the legs. "I’ve seen them compete in marathons and go swimming and mountain climbing," he said. "So never give up!"
【小题1】Monty had an accident in 1986 because_______.