Choose the words or expression and complete the passage （选择最恰当的单词或词语完成短文）

Mobile homes（活动房屋），pulled by specially designed cars have been increasing（增长） in numbers all over the United States．Often，driving along，you can see some mobile homes high on a hill．Some stand under trees （75）___ a river or a lake．They are wonderfully built homes．Sometimes they are as much as 40feet long，with two to five rooms，and you can find many things you need in them．When you park your new mobile home，water，electricity power and （76）___ are connected，and you can enjoy yourself there．

The fact that these homes can be moved doesn't mean they do move（77）___．Sometimes their owners stay for years in one place，plant gardens，build walls and so on．

These homes are often quite expensive．Some even cost 20，000．

Why does a family choose to live in （78）___ home？Well，it's comfortable，easy to keep clean，easy to keep warm，no need to paint．What's more，the fast increase mobile homes in numbers has something to do with the job uncertainty（不确定）．Nobody knows what will happen tomorrow．If a factory closes down，you may be trapped with（被困住） the house you can't sell．However，if you have a mobile home，you can move on easily．

The great selling attraction of these mobile homes is that they can be （79）___every year．If you are doing well，you may change a new mobile home just as you do with a car．There is a ready market for used ones，so the price of the mobile homes is （80）___ than that of cars．