novelty．But now，these fun shelters are appealing to adults too and many are booking themselves in for a few nights among the treetops．

　　These tree house hotels can be found From Europe to Australia．Best of all，they come in a variety of interesting designs!From the traditional'four walls and a roof'habitation，such as at TreeHouse Point，in Washington，North America，to the more artistic Nothofagus Hotel in Chilean Patagonia，whose twelve-sided walls make it look like a beehive．If that doesn't appeal，how about a tree hut?

　　The Free Spirit Spheres resort on Vancouver Island in Canada allows guests to stay in one of three yellow spheres(球体)，which hang from trees．The company was founded in 1998 by Tom Chudleigh，who hand built the huts from cedar wood and fiber glass．Not only are they as safe as houses，they're popular!Mr Chudleigh tells the BBC．

　　Digs(借宿的地方)which are original seem to be a big draw．In Sweden，at the Treehotel numbers have also risen．"Today we have seven rooms and nearly 5,000 guests，"Kent Lindvall explains．Each of the houses there was designed to make use of the light and surroundings．

　　And how about an office?Microsoft，hoping to give its employees thinking space，has commissioned(委托)a tree-building structure from Pete Nelson，tree house book author and designer and builder of tree houses．"Studies show people can work better in nature．They are more productive，"says Mr Nelson．

24．What is the text mainly about?

A．The designs of the tree house hotels．

B．The function of the tree houses．

C．The trend for tree houses．

D．The future development of houses．

25．Why have tree houses become fun shelters?

A．People find few safe houses to live in．

B．They are of novel shape and appealing color．

C．There are no places of amusement for children．

D．Their construction have gotten modernized．