Question

　　1．A train car moves along a long straight track. The graph（曲线）shows the position as a function of time for this train. The graph shows that

　　A．slows down all the time

　　B．speeds up all the time

　　C．speeds up part of the time and slows down part of the time

　　D．moves at a constant speed

　　2．As the diagram shows, there is a fixed superconductor ring, on the right of which lies a bar magnet. There is no electric current. When the magnet is moved to the right, because of electro-magnetic, induction, a certain electric current is produced. Thus the direction of the electric current is ________.

　　A．as indicated by the arrowhead in the diagram. When the magnet is moved away, the electric current will soon disappear.

　　B．as indicated by the arrowhead in the diagram. When the magnet is moved away, the electric current will still remain.

　　C．in the opposite direction. When the magnet is moved away, the electric current will soon disappear.

　　D．in the opposite direction. When the magnet is moved away, the electric current will still remain.  

 

Answer 1

答案：A;D
解析：

1．A 速度一直在减慢。 　　2．D 电流朝相反的方向，当磁铁拿走时，电流仍然存在。

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