问题 填空题

雄奇险秀的长江三峡景色,自古以来就为文人墨客所称颂,北魏著名地理学家、散文学家郦道元就写下了脍炙人口的《三峡》名篇.文中写到春冬的美景时,用“素湍绿潭,回清倒影”作了精要的描绘,句中的“倒影”是光的______现象(选填“反射”或“折射”).2003年6月1日举世瞩目的三峡工程正式下闸蓄水,奔腾千年的滔滔江水被拦入大坝与群山的怀抱,“高峡出平湖”的百年梦想从诗境变为现实,随着上游水位的升高,上游江水的______(选填“重力势能”或“动能”)不断增大.

答案

平静的水面相当于平面镜,水中的倒影是景物在水中形成的像,因此属于光的反射现象;

因为重力势能是物体由于被举高而具有的能,它与物体的质量和被举的高度有关,湖水的水位不断上升,水位的高度在增加,所以湖水的重力势能在不断增加.

故答案为:反射;重力势能.

选择题
阅读理解

阅读理解。

     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

     Please stay oil 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 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.

Wildlife

     Do not feed park wildlife. There have been a few cases at Grand Canyon National Park where deer were

purposely shot because there are plastic bags that left them sick and weak. Hungry deer car be dangerous 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.

1. What can you do first if you want to go camping?

A. Know the permitted.

B. Book campgrounds in advance.

C. Make sure not to make afire.

D. Stop at Mather and Desert View.

2. What can you do first if you want to go camping?

A. Know the permitted.

B. Book campgrounds in advance.

C. Make sure not to make afire.

D. Stop at Mather and Desert View.

3. Why were deer killed on purpose at Grand Canyon?

A. They ate wrong things and become very ill.

B. They were a danger to other gentle animals.

C. They begged food from visitm-3.

D. They kicked and bit visitors.

4. What is the main purpose of the text?

A. To provide travel information.

B. To report some recent news.

C. To teach tourists hiking skills.

D. To introduce the wildlife.