A

The United Stated is rich in national parks.They are well worth visiting ,and make the most of your stay in the US!Before starting a journey,a few things should be kept in mind.

You should wade through www.nps.gov,the official website of the National Park Service .Even though the web page is overly complex and confusing ,it does have exhaustive information on every single park or mountain you will ever want to visit.Park and parking maps can also be helpful in planning your trip.

Perhaps a less well-known fact is that national parks in the United Stated are toughly regulated,with plenty of restrictions.You will need a permit in order to enter a national park.Prices vary depending on permit types(among which are individual permits,vehicle permits,commercial tour permits,water permits ,camping permits and so on).

Last but not least ,make sure not to skip the visitor and information centers on site.They will have the most current  information on weather and road conditions,parking and camping availability,and will give you useful tips on what is worth seeing!

The first and oldest national park in the world ,Yellowstone National Park,spreads over the states of Idaho,Montana and Wyoming.Yellowstone River ,the Mammoth Hot Springs and the waterfalls throughout the park can keep you there for a much longer time than you could have predicted.

There are many other ones that are worth seeing.Plenty of places to visit,just pack your tent ,hit the road ,and you will never regret it!

21.The underlined word in Paragraph 2 probably means____________.

   A. detailed          B. secret           C.useless          D.outdated

22.What can we learn about Yellowstone National Park from the passage?

   A.It is not worth visiting at all.        B. We can view all scenic spots in it in a day.

   C.It is a modern park.                      D.It is very large in size.

23.What is mainly talked about in the passage?

  A. Restrictions and limitations in American national parks.

      B.The main sites that are worth visiting in American national parks.

  C.Some information on American national parks and advice on visiting them.

  D.The first and oldest national park in the world.