单选题 The last part of this century will be an age of space exploration such as man has never known. There are eight planets, at least thirty satellites, and thousands of small stars to be explored. 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 ten times as great as the continents of the earth.
Exploring space may seem terrifying to some people. No doubt explorers of the past were terrified by the great empty oceans that lay before them. They conquered (克服) 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 everyone they knew at home. Space explorers will not face such great loneliness. Even when they travel far away from the earth, they will be able to send messages back.

单选题 Future space exploration will______.
A. be more difficult than it was in the past
B. be more dangerous than in the past
C. be more lonely than in the past
D. cover a larger area than any exploring done before

单选题 If the land area of the earth is about 55,000,000 square miles, the area that can be explored in space is probably______.
A. 55,000,000 square miles B. 70,000,000 square miles
C. 13,720,000 square miles D. 550,000,000 square miles

单选题 Man will probably explore______.
A. areas on which spaceships can land B. only the largest planets and satellites
C. only a few of the large planets D. all the land in space

单选题 The writer thinks that this area will be explored______.
A. in the far distant future B. at the end of this century
C. in the beginning of the next century D. at the end of the next century

单选题 The writer thinks that modem explorers______.
A. may be lonely B. can not conquer their fears
C. will keep in touch with the earth D. can not have connection with the earth