摘要：5．From the passage , we know X-rays are . A．invisible B．changeable C．white D．bright B A shopping center is a place where many different shops and stores are collected under one roof . You can buy everything there , and there are also banks restaurants and , sometimes , a post office . There are other places in the United States which are called five-and –ten-cent stores because they used to sell things for 5 to 10 cents . Today they sell almost anything and some of the things cost several dollars . Supermarkets are found in all the cities . They sell food and many other goods . You walk around the supermarket , choose the things you want , put them into a special basket prepared by the store and pay for them all together at the door . Supermarkets often stay open later than other stores . Stores are usually open every day of the week except on Sunday . Some close on Saturdays in July and August .
X-rays were first discovered by a German scientist, Wilhelm Konrad Rontgen, in 1895, almost by accident．He and several other scientists were experimenting with passing electric currents through certain gases in a special glass tube from which the air had been moved．One day Rontgen noticed that, even when the tube was covered with black paper, some strange kind of radiation was coming through and making a screen nearby glow．Ronghen could not see anything coming out of the tube, but then he discovered that if he put the screen in the next room on the other side of a closed door, the rays could pass not only through black paper but also through wood．
The next thing he found out was that if he put his hand between the rays and a photographic plate, the rays would print a shadow of the bony framework of his hand 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 Rontgen made the first X-ray picture of a hand, showing just how the bones in the hand fit together．
(1)
What puzzled Rontgen one day during his experiment was ________．
[ ]
A．
some passing electric current
B．
some radiation coming through the covered tube
C．
the black-paper-covered tube
D．
the screen nearby
(2)
The screen didn’t stop glowing even when ________．
[ ]
A．
it was moved to the next room
B．
it was moved to the other side of the room
C．
the door was closed
D．
the black paper was moved from the tube
(3)
The rays proved to be incapable of passing through ________．