When the algae have done theri work, the atmosphere will become cooler,but befor man can set foot on Venus it will be neccessary for the oxygen to produce rain. The surface of the planet will still be too hot for man to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.

　　1.Inte long run, the most insoluble problem caused by population growth on earth will probably be the lack of ______.

　　a.food

　　b.oil

　　c.space

　　d.resources

　　2.Carl Sagan believes that Venus might be colonized from earth because _____

　　a.it might be possible to change its atmosphere

　　b.its atmosphere is the same as the earth's

　　c.there is a good supply of water on Venus

　　d.the days on Venus are long enough

　　3.On Venus there is a lot of ________.

　　a.water

　　b.carbon dioxide

　　c.carbon monoxide

　　d.oxygen

　　4.Algae are plants that can____.

　　a.live in very hot temperatures

　　b.live in very cold temperatures

　　c.manufacture oxygen

　　d.all of the above

　　5. Man can land on Venus only when_______.

　　a.the algae have done their work

　　b.the atmosphere becomes cooler

　　c.thereis oxygen

　　d.it rains there

　　答案：cabdd

　　As she walked round the huge department store,Edith reflected how difficult it was to choose a suitable Christmas present for her father.She wish that he was as easy to please as her mother, who was always delighted with perfume

　　Besides,shoppong at this time of the year was a most disgreeable experience :people trod on your toes,poked you with their elbows and almost knocked you overin their haste to get to a bargain ahead of you.

　　Partly to have a rest, Edith paused in front of a counter where some attracive ties were on display. "They are real silk," the assistant assured her, trying to tempt her. "Worth double the price." But edit knew from past experience that her choice of ties hardly ever pleased her father.

　　She moved on reluctantly and then quite by chance, stopped where a small crowd of man had gathered round a counter. She found some good quality pipes on sale-----and the prices were very reasonable. Edith did not hesitate for long : although her father only smoked a pipe occasionally, she knew that this was a present which was bund to please him.

　　When she got home,with her small well-chosen present concealed in her handbag, her parents were already at the supper table. Her mother was in an especially cheerful mood, "Your father has at last to decided to stop smoking." She informed her daughter.

　　1.Edith's father _______.

　　a.did not like present

　　b.never got present

　　c.preferred ties

　　d.was difficult to choose a present for

　　2.The assistant spoke to Edith because she seemed_______.

　　a.attractive

　　b.interested in ties

　　c.tired

　　d.in need of comfort

　　3.Edith stopped at the next counter_________.

　　a.purosely

　　b.suddenly

　　c.unwillingly

　　d.accidentally

　　4.Edith's father smoked a pipe_______.

　　a.when he was obliged

　　b.on social occasions

　　c.from time to time

　　d.when he was delighted

　　5.Shopping was very disagreeable at that time of the year because_______.

　　a.coustomers trod on each other's toes

　　b.coustomers poked each other with their elbows

　　c.customers knocked each other

　　d.customers were doing their shopping in a great hurry

　　答案：dbdcd