填空题

Five million people visit Grand Canyon in the US every year. For the purpose of helping protect Grand Canyon for your fellow visitors and future generations, please follow the guidelines below.
Camping
To protect the park, camping is allowed only within permitted campgrounds. Permits are required for overnight camping at the North Rim. Advance booking can be received by mail. Please write: Information Center, P.O. Box 129, Grand Canyon, AZ 86023.
Fires
Because of the extreme fire danger, campfires are not allowed except at Mather and Desert View campgrounds. Collection of firewood is not allowed either.
Hiking(远足)
Please stay on permitted paths. Otherwise you may destroy desert plants. Pack out what you pack in, so you leave no signs of your visit. It is important to keep in mind that you are in a national park where wildlife exists.
Weather
The weather at Grand Canyon can change very quickly. With so much rock, lightning(闪电) causes a particular danger during sudden summer storms. These storms also frequently bring floods inside valleys, a danger to hikers. Watch the skies and check daily weather reports.
Wild life
Do not feed park wildlife. There have been a few cases at Grand Canyon National Park where deer(鹿) were purposely shot because they ate plastic bags that left them sick and weak. Hungry deer can be a danger and have kicked and bitten visitors at Grand Canyon. Some other animals Will also beg and bite. For your own safety and the well-being of the animals, please do not feed wildlife, no matter how gentle they may appear.
Guidelines
Camping:1． (47) campgrounds in advance.
2．allowed only within permitted campgrounds.
Fires:1．not allowed except at Mather and Desert View campgrounds.
2．not allowed to (48) firewood.
Hiking:1．stay on permitted paths.
2． (49) everything you bring in.
Weather:Watch the skies and50) daily weather reports.
Wildlife: Don’t (51) Bark wildlife.