A
Fishing
Fishing is a wonderful way to enjoy the sport and see beautiful streams，ocean，lakes and rivers all over the United States.National Parks offer both freshwater and saltwater fishing.Check with the state fishing rules for the dates and more fishing information，and you should have license.It is always important to respect the park you are fishing in to keep the clear waters that protect the natural fish populations and food sources.
Cross country skiing
It is another popular way for the whole family to visit and see beautiful winter landscapes.Many parks have several excellent lines for cross country skiing.Several National Parks will offer advanced trails for skiing.Cross country skiing is a wonderful way to experience natural life of the parks during the winter season.
Rock climbing
The US National Parks offer some of the rock climbing and mountaineering in the world.Rock climbing and mountaineering are usually sports kept for people with a bit of experience.Both sports need having the proper equipment and knowledge for safety reasons.Many National Parks offer established climbing routes that will have a wide range of difficulty levels.It is important to check weather conditions beforehand and what’s more, never climb alone.
Cycling
Cycling is an excellent and convenient way to travel around the National Park or area where you are staying.Bringing along bicycles allows you to just get up and go wherever you are.It is important to check beforehand as to where cycling is allowed.Most National Parks only allow biking on the paved and backcountry dirt roads throughout the parks.Look into the area you will be camping in，there may be roads specifically for cycling.
【解题导语】 本文主要介绍了在美国国家公园的四个有益的户外活动。
21．If you go fishing in the National Parks you should ________．
A．show respect for the workers
B．fix a date and place ahead of time
C．do anything according to the orders
D．protect the number of the fish
C 解析：细节理解题。根据Fishing一节中的“Check with the state fishing rules for the dates and more fishing information，and you should have license.”可知选C。
22．All the following are important to rock climbing EXCEPT ________．
A．knowledge for safety
B．weather conditions
C．climbing experience
D．modern equipment
D 解析：细节理解题。根据Rock climbing一节的内容可知，该部分提到了攀岩需要具备的若干条件，A、B、C三项均有提及，虽然也提到了设备，但没有说明是指现代设备。故选D。
23．What would be the best title for this passage?
A．Which Is More Wonderful?
B．Activities in the National Parks
C．A Good Plan for Traveling
D．Where to Go for Your Vacation?
B 解析：标题归纳题。综合全文内容看，本文主要介绍了在美国国家公园的四个有益的户外活动。
