1 . 阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。

Before the mid-2th century,     1     (travel) into space was an impossible dream. However, some scientists were     2     (determine) to help humans realise their dream to explore space. The USSR focused     3     sending people into space after 4 October, 1957. Though the terrible disasters made people sad and     4     (disappoint), people never gave up     5     (explore) space exploration. This is     6     they believe in the importance of space exploration. China has become the third country in the world to     7     (independent) send humans into space in 2003. Europe, the US and China all have plans to     8     (far) study and explore planets. Despite the     9     (difficulty), scientists hope futher discoveries will enable us     10     (understand) how the universe began and help us survive well into the future.

2 . Edmund Halley was an English scientist who lived over 200 years ago. He studied the observations of comets which other scientists had made. The orbit of one particular comet was a very difficult mathematical problem. He could not figure it out. Neither could other scientists who dealt with such problems.

However, Halley had a friend named Newton, who was a brilliant mathematician. Newton thought he had already worked out that problem, but he could not find the papers on which he had done it. He told Halley that the orbit of a comet had the shape of an ellipse.

Now Halley set to work. He figured out the orbits of some of the comets that had been observed by scientists. He made a surprising discovery. The comets that had appeared in the years 1531, 1607, and 1682 all had the same orbit. Yet their appearances had been 75 to 76 years apart.

This seemed very strange to Halley. The different comets followed the same orbit. The more Halley thought about it, the more he thought that there had not been three different comets, as people thought. He decided that they had simply seen the same comet three times. The comet had gone away and had come back again.

It was an astonishing idea! Halley felt certain enough to make a prediction of what comet would happen in the future. He decided that this comet would appear in the year 1758. There were 53 years to go before Halley’s prediction could be tested. In 1758 the comet appeared in the sky. Halley did not see it, for he had died some years before. Ever since then that comet has been called Halley’s comet, in his honor.

1. Halley made his discovery ________.

A．by doing experiments	B．by means of his own careful observation
C．by using the work of other scientists	D．by chance

2. Halley made a surprising，but correct prediction in the year ________.

A．1704

B．1705

C．1706

D．1707

3. This passage in general is about ________.

A．Halley and other scientists	B．the orbit of a comet
C．Newton and Halley	D．Halley and his discovery

4. What can we know from the text?

A．Edmund Halley was an American scientist.	B．Halley made his discovery by doing experiments.
C．Newton was a famous mathematician.	D．The orbit of a comet had the shape of a circle.