一物体静止在升降机的地板上，在升降机加速上升的过程中，地板对物体的支持力所做的功
题型：不定项选择
问题：
一物体静止在升降机的地板上，在升降机加速上升的过程中，地板对物体的支持力所做的功等于：[ ]
A、物体势能的增加量
B、物体动能的增加量
C、物体动能的增加量加上物体势能的增加量
D、物体动能的增加量加上物体克服重力所做的功
题型：不定项选择
One night last February, a seventeen-year-old Duffy drove home along a winding road, he saw a strange light thrown against the tree. “I knew it wasn’t the moon”, he said. “I drive this road all the time and I notice little things out of place.”
Duffy stopped his car and got out to examine. Below him far down in the deep valley lay a broken car with its headlights on. Thirty minutes earlier, a man had driven off the edge of the road, which h
as no guardrail. His car fell and rolled end over end, landing on its top more than two hundred feet below.
Duffy rushed to call for help, then returned and got down to reach the injured driver. Snow covered the valley and the temperature was below freezing. After struggling back up the cliff, Duffy took off his jacket and shirt and wrapped the injured man in time, along with the blankets from his car.
Life-saving deeds are starting to become usual action for Duffy, the oldest of seven children. When he was 12, he saved his ten-year-old brother from drowning. Two years ago, his three-year-old sister ate rat poison, and Duffy cleaned out her mouth, make her drink milk to protect her stomach and called doctors.
“We have tried to teach the children good values, and it looks like we have got some reward for it.” His father says.
小题1:.The strange light came from ________.
A．The bright moon.
B．Duffy’s car.
C．The broken car in the valley
D．an unknown place小题2:.The phrase” landing on its top” means the car lay_________.
A．on the top of the cliff
B．with its wheels upward
C．with its head upward
D．on the road as usual小题3:. Duffy wrapped the man because_________.
A．he was badly injured
B．he had lost too much blood
C．he had nothing on
D．it was too cold that day小题4:. From the above article, we can see Duffy has saved ________ at least.
A．two
B．three
C．four
D．five