27、Astronauts have already visited the Moon and lived on space stations．They've never been to another planet，but they might visit Mars soon．Astronauts will spend about six months getting to the planet，then about two years on the planet and about six months travelling back to the Earth．They’ll be away from the Earth for about three years，so they'll need much food．

It's very expensive to take food into space．It costs about 120 000 dollars to carry something that weighs（重）one kilo（千克）．So an apple on Mars could cost 20000 dollars! Of course，they will need to take much food with them to feed the astronauts for three years．This amount of fresh food can't stay fresh，and is very expensive to take，so they need to find food that is not very heavy．

At the moment，astronauts in space stations eat dried food．It's very light，so it doesn't cost much money to carry it into space．But astronauts stay healthier and happier if they eat fresh food，In the future，astronauts on Mars may grow vegetables like carrots and lettuce（生菜）．

Astronauts on Mars will probably have special machines．They'll use these machines to change beans（豆）into food that tastes like meat or cheese．They probably won't eat real meat or cheese because it won't he possible to keep animals in space．

1．Which planet do the astronauts plan to go to next?

A．Mars．                B．Space．               C．The Moon．

2．How long will it take to get to Mars?

A．About three years． B．About two years．   C．About six months．

3．Why do the astronauts eat dried food?

A．Because it is cheap to carry．                      B．Because it is cheap to buy．

C．Because it is very healthy．

4．What may astronauts do in the future?

A．Eat only dried food．                                  B．Grow some fresh vegetables on Mars．

C．Grow food in their spacecraft．

5．What will they get from beans?

A．Apples．                                                   B．Food that tastes like meat or cheese．

C．Real meat and cheese．