49.(　 ) Who can enjoy natural climate?

A. People living under glass domes.

B. People living in cave cities.

C. People living in vertical cities or floating cities.

D. People living in cave cities or floating cities.

48.(　 ) What kind of the city described in the passage covers less land?

A. The floating city.

B. The horizontal city.

C. The glass-domed city.

D. The vertical city.

47.(　 ) What do you think the underlined word "horizontal" in paragraph 2 means?

A. Ladder-shaped.

B. Flat.

C. Undersea.

D. Underground.

46. Orbiting the earth in a skylab, the astronauts_________.

A. warmed their food in special freezers before eating it

B. slept not by lying flat in beds but standing up in hanging bags

C. walked with their feet on the floor of the skylab with special devices

D. used a closed-in shower so that the water would not float out of the skylab

(D)

Scientists are thinking about cities of new kind, which are quite different from those we live in. Some building designers are designing new cities in the desert. The cities wi1l he 1lnder g1ass demes(圆顶) in which heating and cooling system will control the climate (气候). TI1e temperature there will, of co1lrse l always he comfortable for people to live in, for there will never he any heavy rain or snowstorm. But this seems to he unreasonable because it is believed to he too closed a world for its inhabitants(居民).

Perhaps people will live in high vertical(垂直的) cities which are large enough to contain all the necessities of life. This kind of cities will use less land than horizontal cities, so they can provide more homes for people and thus

will be helpful to Small countries that have 1arge population.

Another idea which small countries and island countries will he interested in is the floating city. Monaco, for example, has already built homes, stores and offices on the water of the Mediterranean Sea. And a Japanese Designer has suggested a plan for constructing buildings on bridges over Tokyo Bay(海湾).

Long long ago o1lr ancestors lived in caves, as is known to us all. But do you know some scientists are now thinking that we should go hack to living in caves? The caves of future will, of course, be different from those of the Stone Age. Computers will control light and climate. Farms and parks will be on the land over the cave city. When you want to go to the countryside or a park 1br your holiday, just a short ride in a lift will take you there.

45.(　 ) How did the astronauts drink water or other liquids?

A. They drank water and other liquids just as babies do.

B. They used baby bottles to drink water and other liquids.

C. They drank water and other liquids prepared for babies.

D. They drank water and other liquids left by young babies.

44.(　 ) In the skylab, the astronauts ate______.

A. food by squeezing it into their mouths

B. food more difficult than they did in spaceships

C. bread, meat, vegetables, and fruits kept under covers

D. the food kept in tubes or bags prepared beforehand

43.(　 ) Sometimes the astronauts enjoyed the lack of gravity because______.

A. they thought it was fun in skylab

B. they and the objects were weightless

C. things floated freely unless held down

D. the skylab was beyond the earth's gravity

42.(　 )_______ is the second largest country which has more HIV infection all over the world.

A. China　　　　　 B. South Africa　 C. India　 D. Thailand

(C)

ars ago, Mala was a typical middle-class Indian What was it like to live in space?

Imagine orbiting (环轨道运行) the earth once every ninety-three minutes. Imagine traveling through space at more than twenty-seven-thousand kilometers an hour. That is what the skylab astronauts did. During that time they ate, slept, and did most of the things people do on the earth. But there was one big difference. There was no gravity.

Gravity is the force that holds us down to the earth. Skylab was beyond the reach of the earth's gravity. People and objects were weightless. They floated freely unless held down.

At times, the skylab astronauts enjoyed the 1ack of gravity. They could float like bubbles through the spaceship. They could hang upside down like bats(蝙蝠). They could do sticks like circus acrobats(杂技演员).

At other times, however, they did not enjoy the lack of gravity. with no gravity, their food new right off the plate. And a dropped tool just floated away.

Skylab was a space house. But living and working in it were very different from living and working in a house on the earth.

Skylab had a workshop, a s1eeping area, a kitchen, and a bathroom. Unlike a bedroom on the earth, the sleeping area did not contain beds. It had hanging bags. The astronauts slept standing up in the bags. They could not lie flat in a normal bed, because they would float off.

The bathroom in skylab had a shower. So, the astronauts could wash themselves. The shower was completely closed in. This was necessary to prevent the water frome floating throughout the spaceship. Water and wastes had to be pulled by pipes into storage containers.

The astronauts in skylab wore shoes that had special devices on the bottoms. These devices linked with similar devices on the floor of the spaceship. This kept the astronauts in one place as they worked or ate.

On the two earlier flights, astronauts had eaten from tubes(管) or bags. They just squeezed(挤压) the food into their mouths. On skylab, eating was a more normal activity.

The astronauts ate bread, meat, vegetables, and fruits. They stored the food in freezers. They warmed it in special heating devices. Magnets (磁铁) held down their knifes, forks, and spoons. Covers kept the food from floating away. The astronauts drank water and other liquids from p1ashc container similar to baby bottles.

41.(　 ) According to the passage, the main means that AIDS spreads in Asia is through_______.

A. blood　　　　　 B. unsafe sex　　 C. love　　 D. drugs