Early in the 20th century it was noticed that odd things were happening to some science experiments. Rays of a strange kind were reaching them. They were like X rays, but they were not X rays.
Scientists wondered if the rays could be coming from far outside the earth. To find out, and to learn more about these strange rays, they went here, there, and everywhere studying them. They went into caves and into the great cracks in glaciers. They went deep down under the sea and up to the tops of high mountains. In balloons they went higher in the air than anyone had ever gone before. They even went into such out-of-the-way places as the mouth of a big cannon and the underside of great piles of salt. Finally they could say for certain that the rays come from out beyond the earth. They named them cosmic rays.
Knowing about cosmic rays has proved useful in important ways. It brought about, for instance, the use of Carbon 14 in dating things from the past. And it has led to a far better understanding of the great universe around us.
【題組】21. What do the “odd things” refer to in the 1st paragraph?
(A) sun rays (B) moon rays (C) cosmic rays (D) X rays
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