阅读短文，完成下列各题。
Snow fell on the mountain. It snowed and snowed. The snow did not melt (融化). It became deep and
heavy. The snow on the bottom pressed (挤压) together, it became ice.
The ice was very wide and thick. It began to move down the mountain. It was like a river of ice. It was a
glacier (冰河).
Sometimes the glacier moved only a few inches (英寸) each day. As it moved, it took rocks and dirt with it.
It changed the land. In some places, it left hills. In some places, when the glacier melted, it made rivers and
lakes.
A million years ago, there were many big glaciers. Glaciers covered many parts of the world. The glaciers
changed the land.
Glaciers are still at work today. A glacier in the north of Canada is cutting a new path (路) down the side of
a mountain. This glacier will change the land, too.
1. The snow that fell on the mountain .[ ]
A. became snowman
B. melted
C. became ice
D. turned to rain
2. The word in the story that means a river of ice is ________.
3. The story says, "The snow did not melt. It became deep and heavy". The word "it" means .
4. Which of the following does this story lead you to believe? [ ]
A. There are not as many glaciers as there used to be
B. Glaciers do not change the land as they move over it.
C. Glaciers are found only in warm places.
5. How fast did the glacier move? (Which sentence is exactly like the one in your book?)[ ]
A. Sometimes the glacier moved only once a year.
B. Sometimes the glacier moved over ten miles each day.
C. Sometimes the glacier moved only a few inches each day.
6. The main idea of the whole story is that _______. [ ]
A. snow is heavy
B. the high land never changes
C. glaciers changed the land
，平均速度相等，所以A正确；匀变速直线运动，中间时刻的瞬时速度等于平均速度，所以B正确
所以t1＞t2，所以C错误；
，
，t1＞t2，所以a1＜ a2，所以D错误。