根据短文回答 41～45 题。
The National Park service
America's national parks are like old friends。You may not so e them for years at a time。but just knowing they're out there makes you feel better.Hearing the names of these famous old friends-Yosemite,Yellowstone,Grand Canyon-revives memories of visits past and promotes dreams of those still to comE.
From Acadia to Zion。369 national parks are part of a continually evolving system. Ancient fossil(化石的)beds,Revolutionary War battlefields,magnificent mountain ranges,and monuments to heroic men and women who molded this country are all a part of our National Park System(NPS).The care and preservation for future generations of these special places is entrusted(托管)to the National Park ServicE.Uniformed Rangers,the most visible representatives of the Service,not only offer park visitors a friendly wave,a helpful answer or a thought-provoking history lesson,but also are skilled rescuers,firefighters,and dedicated resource protection professionals(专业人员).The National Park Service ranks also include architects,historians,archaeologists,biologists,and a host of other expels who preserve and protect everything from George Washington's teeth to Thomas Edison's wax recordings.
Modern society has brought the National Park Service both massive challenges and enormous opportunities.Satellite and computer technologies are expanding the
educational possibilities of a national park beyond its physical boundaries.Cities struggling to revive their urban cores are turning to the Park Service for expert assistance to preserve their cultural heritage, create pocket parks and green spaces, and re-energize local economies. Growing communities thirsty for recreationally outets are also working with the NPS to turn abandoned railroad tracks into bike and hiking trails, as well as giving unused federal property new life as recreation centers.
To help meet these challenges and take advantage of these opportunities the National Park Service has formed partnerships-some dating back 100 years, some only months old-with other agencies, state and local governments, corporations, American Indian tribes and Alaska Natives, Park Fiends groups, cooperating associations, private organizations and commonly groups.
第 41 题 Why are America's national parks like old friends?（ ）
A.Because knowing they are there makes you happier
B.Because they are very old
C.Because they are tourist attractions
D.Because they are very famous