毫无疑问他们将提前完成这项工作。

误：There is no doubt whether they will finish the work ahead of time．

正：There is no doubt that they will finish the work ahead of time．

语篇理解

    The last part of this century will be an age of exploration（探险）such as man has never known．There are 9 planets, at least 30 moons, and thousands of asteroids（小行星）．Their total area is about 250 times that of the earth．Spaceships will not be able to land on some of them．But that still leaves to be explored an area 10 times as great as the continents of the earth．

　　 Exploring space may seem terrifying to some people．No doubt （毫无疑问）explorers of the past were terrified by the empty oceans that lay before them．They conquered（征服）their fears, crossed the oceans, and built the New World．

　　 In the past when explorers set sail into the unknown, they had to say good-bye to everything they knew at home．Space explorers will not face such great loneliness．Even when they travel far beyond the sun, they will be able to send messages back．

1．According to the first paragraph, ______．

[　　]

A．man has not known how to explore space yet

B．spaceships will be able to reach some places in space

C．an area to be explored if as large as the continents of the earth

D．the total area to be explored if about 250 times that of the earth

2．Future exploration will ______．

[　　]

A．be more difficult than it was in the past

B．cover a larger area than any exploring done before

C．be more dangerous than in the past

D．be more lonely than in the past

3．If the land area of the earth is about 55×106 square miles , the

  area that can be explored in space is probably ______ square miles.

A．495×106　　  B．165×107

C．55×107　　   D．1375×107

4．Now space explorers will not feel lonely because ______ .

A．they are so excited that they forget everything at home

B．they have already said good-bye to everybody they know

C．they have been able to conquer fears and loneliness

D．they keep in touch with the earth at any time

5．The writer thinks that all the areas that can be explored are to be explored ______ .

A．at the end of the nineteenth century

B．at the end of the next century

C．at the end of the twentieth century

D．in the far-distant future