It seems to be strange to you there is a blind spot(盲点)on the eyes, Here is an interesting experiment(实验)that can make something disappear, when one eye is open.
Make a card about the size of a postcard and write two English letters L and R on it, Lon the left and R on the right. First, hold the card about 80 cm away and you see both the letters. Then close your right eye and look at the letter R only with your left eye. And now, as you move the card slowly towards you, you' 11 find the letter L disappearing. But if you move the card nearer to your face, the letter will be seen again. Now do the same experiment with your left eye closed, you'll find the letter R disappearing.
Why does the letter disappear? It is because there is a blind spot on the eye. When the image（影像）of the letter falls on the blind spot, it won't be seen. That is why either of the letters disappears．
小题1:The writer of the passage thinks that_______ there is a blind spot on the eye.
A．few people know
B．no one knows
C．only you know
D．all the people know小题2:The word "disappear" in the passage means_______ in Chinese.
A．驱散
B．消散
C．消失
D．遗失小题3:You fail to see the letter L in the experiment because _______.
A．your eyes are poor
B．its image falls on the blind spot
C．your left eye is not open
D．you move it close to your eye小题4:In which order(顺序)should you do the experiment?
①Hold the card ②Move the card nearer ③Close your right eye
④write two English letters ⑤Look at the letter R ⑥Make a card
A．④⑥①②③⑤
B．①③⑥④⑤②
C．⑥①④③②⑤
D．⑥④①③⑤②小题5:The passage mainly tells us_______.
A．how to find the blind spot
B．an interesting experiment
C．where the blind spot is
D．there is a blind spot on the eyes.
sin100πtV的交流电源，副线圈接一个R=27.5Ω的负载电阻．则下述结论正确的是（ ）
W