It is interesting how NASA(美国航空航天管理局)chose their astronauts for landing them on the moon. They chose men   1  the age of twenty and thirty-five. There were about fifty of them , Many were  2  air pilots.  3  were scientists with two or three degrees. NASA telephoned each man they were going to choose ;told him the plans and the   4  they might get in. They then asked him if he was willing to be trained as an astronaut. “How could any man   5  such an exciting job?”One of them said, “Dangerous? Of course. It’s dangerous   6  most exciting”

The health and physical condition of   7  was, of course, very necessary.  8  those in very good health and physical condition were chosen.

While being trained to be astronauts. they went through many  9 . They studied the star and the moon , and they also studied geology, the science of rocks. This was necessary   10  astronauts would have to look for rocks on the moon. They would try to find rocks which might help to tell the   11  of the moon. They were all   12  to fly in helicopters （直升飞机）。These helicopters landed   13  down to give them some experience of the way the spaceship would  14  land on the moon , They were also taught the   15  facts about the conditions in space. They learnt all the technical details of the spaceships and rockets. They visited the scientists and engineers who   16  them. They visited the factories where they were   17 . They learnt how every   18  of a space-ship and its instruments work. They also learnt every detail of ground-control  19 .

In a word , to be chosen as an astronaut. one must be in good health,  20  in science and good at piloting

    KEY: 1－5 ABCAD  6－10 ACBCB  11－15 CBDDC 16－20 CBACD