第三部分：阅读理解（共20小题，每题2分，满分40分）
阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项，并在答题卡上将该项涂黑。
A
The luxury of eating an apple on Mars could cost as much as US $22,000. That's because it costs about US $120,000 to launch a kilogram of anything into deep space. So getting enough food into orbit is a big problem facing astronauts on a trip to Mars.
After NASA (National Aeronautics and Space Administration) has no current plans to send astronauts to Mars, related research is being carried out—including the production of food. Astronauts on the international Space Station usually eat primarily freeze-dried food to which they add water. However, the weight of the packaging—almost as much as the food inside—costs a lot of money. The biggest problem of all is a psychological one.
Scientists believe that astronauts will suffer without the variety offered by fresh vegetables. The answer is to grow at least some of the food. On a short trip it is imagined that astronauts will eat vegetables such as lettuce, spinach and carrots grown in a refrigerator-sized unit known as a "salad machine". On longer journeys they will actually grow vegetables in greenhouses on Mars. Martian astronauts will eat a vegetarian diet since it will not be practical to raise animals. To make up for the lack of meat, recipes have been created to add as much variety to the diet as possible, using only a basic number of products. It uses heat and mechanical force to transform soybeans into meat and cheese substitutes（代替品）. The prized result of this research is a purely vegetable-based pizza with meat and cheese substitutes .
41. What is the best title for this story?
A. Space Food B. Astronauts' Problem
C. The Packaging of Space Food D. Mars Rover-Spirit
42. What is the main problem with the diet of astronauts on the international Space Station now?
A. The packaging is too expensive.
B. Only fresh vegetables are offered.
C. Too much water is needed for dried food.
D. There are not enough choices of food.
43. What is the "salad machine" in the spaceship for?
A. It stores vegetables. B. It grows vegetables.
C. It cooks green salad. D. It mixes green salad.
44. From the passage we know that the diet plan for Martian astronauts is short of .
A. Vegetables. B. A special kind of Pizza. C. Meat. D. Soybeans
