问题 选择题
如图所示的LC振荡电路,在某时刻的磁场方向如图所示,则下列判断不正确的是(   )

A.若磁场正在增强,则电场能正在减少,电容器上极板带正电

B.若磁场正在减弱,则电场能正在增强,电容器上极板带正电

C.振荡电流的变化周期为:

D.电场能量的变化周期为:π

答案

答案:A

阅读理解

阅读理解。

      Every year, earthquakes are responsible for a large number of deaths and vast amounts of destruction(破坏) in various parts of the world. There are about a million quakes a year. Fortunately, however, not

all of them are destructive. The intensity (强度) of an earthquake is measured on the Richter Scale, which goes from zero upward. The highest magnitude recorded to date is 8.9Major damage generally occurs

from quakes ranging upwards from 6.0.

     The actual cause of earthquake itself is the breaking of rocks at or below the breaking of rocks or

below the earth's surface. This is produced by pressure which scientists believe may be due to a number

of reasons, two of which are the changed of the earth's crust (外壳) and continental drift(漂流).

      In order to minimize the damage and to decrease some of the pain resulting from earthquakes,

scientists are working on ways to improve accurate prediction. Two kinds of the instruments now in use

to achieve this goal are seismograph(地震仪) and tilt (倾斜) meter. The former records any shaking of

the earth. Seismologists ca accurately record the exact time, location and size of an earthquake. The latter, as the name suggests, is used to record any changes in the tilt of the land.

1. Which of the following statements is NOT true, according to the passage?

A. The highest magnitude of earthquake recorded is 8.9

B. Major damage usually happens when the intensity of an earthquake is below 6.0

C. Scientists usually use seismographs and tilt meters to predict earthquakes now.

D. Continental drift may cause an earthquake.

2. What's the main idea of the passage?

A.  Earthquakes can cause a lot of damage.

A.Scientists are working hard to predict the earthquakes.

B.The reason why earthquakes happen.

C.Introduce the earthquake and its prediction.  

3. Where does the passage mot likely come from? 

A. A newspaper.  

B. A report    

C. A science magazine.    

D. A history book.  

单项选择题