12．
Imagine you are living in a moving house．Inside the house，there is a small kitchen，bathroom and bedroom．
Everything you need is close at hand．
In the US，you can really see these moving houses on the mad．They are called recreational vchicles（RV，房车）．People call them houses on wheels．When it's holiday time，the whole family often gets into this lovely house
and hits the road for a trip across the country．
Compared to a real house，this home on the road is small for a family who has to spend every hour of every day together．But the best thing about it is that it changes your journey into a free exploration．
You can drive as long as you like without worrying about finding hotels．Or you can just stop somewhere nice and stay for a few weeks．You may also come across other families who are on road trips．Together，you take out your tents and snacks．It's camping time with a lot of chat and laughter．
Of course，RVs are not always convenient（便利）．They can sometimes break down and you have to spend time mending them．But this type of road trip still wins people's hearts because they can go whenever and wherever they want．
根据短文内容，从题中所给的A、B、C、D四个选项中选出最佳答案．
53．ARVs，everything you need is close at hand．
A．Inside
B．Outside
C．Behind
D．Beside
54．In the US，people call RVs movingC，
A．cars
B．wheels
C．houses
D．buses
55．Which of the following about RVs is TRUE？D
A．They don't have any wheels
B．They are always convenient．
C．They are bigger than real houses
D．They may break down sometimes．
56．Why do people prefer traveling in RVs？B
A．They like eating snacks in RVs．
B．They can explore their journey freely．
C．They may leave RVs in hotels for a few weeks．
D．They will never come across other traveling families．
57．What's the best title of the passage？C
A．A Road Trip
B．A Wonderful House
C．Moving Homes to Travel
D．Holiday Life in the US．
As space science develops，man has learned more and more about space．Space is not only amazing but also dangerous．While working in space，spacemen are facing danger as well as success．
