Question

　　Once Wilhelm K．Roentgen and several other scientists were experimenting with passing electric currents through certain gases in a special glass tube from which the air had been taken away. Then one day Roentgen noticed that though when the tube was covered with black paper, some strange kinds of radiation was coming through and making a screen nearby glow. Roentgen could not see anything out of the tube, but then he discovered that if he put the screen in the next room on the other side of the closed door, the rays still seemed to affect it. The glowing screen showed that the rays could pass not only through the black paper but also through wood.

　　The next thing he found out was that if he put his hands between the rays and a photographic plate（感光板）, the rays would print a shadow of the bone framework（骨架）of his hands on the plate. In fact, the rays could pass as easily through the fleshy part of his hand as through the black paper, but hardly at all through the bone. So Roentgen made the first X-ray picture of a hand showing just how the bones in the hand fitted together.

　　Roentgen called this unknown rays X-rays, but other scientists called them Roentgens rays in honor of the man who first found them.

(1) Roentgen discovered X-rays ________.

[　　]

A．by working hard

B．by chance

C．by doing experiment after experiment

D．with the help of several other scientists

(2) What was in the special glass tube?

[　　]

A．Air.

B．Nothing.

C．Nothing but gases.

D．None of the above.

(3) We may conclude that the rays Roentgen found were ________.

[　　]

A．dangerous

B．invisible

C．colorful

D．poisonous

(4) What could X-rays hardly pass through?

[　　]

A．Wood.

B．Glass.

C．Bones.

D．Black paper.

Answer 1

答案：B;D;B;C
解析：

(1) B 此题为推理判断题，由文中所提供的信息可知。(2) D 由文中“with passing electric currents through certain gases in a special glass tube”可知。(3) B 由文中“Roentgen could not see anything out of tube...”可知。(4) C 由文中“...hardly at all through the bone”可知。