One of the most popular activities enjoyed by Americans is spending time in forests and walking along paths through the country.This activity，called hiking，has led to the creation of paths throughout the United States.
One of the longest is the Appalachian National Scenic Trail.The trail is the first completed part of the National Trails System.The trails system was established by Congress and the president in 1968.The Appalachian Trail is more  than 3,400 kilometers long.It starts in the northeastern state of Maine and ends in the southeastern state of Georgia.The trail goes through 14 states.They are Maine，New Hampshire，Vermont，Massachusetts，Connecticut，New York，New Jersey，Pennsylvania，Maryland，West Virginia，Virginia，Tennessee，North Carolina，and Georgia.
The path takes walkers through the Appalachian Mountains.They extend from the Canadian province of Quebec to the southern American state of Alabama.
The Appalachian Mountains are among the oldest on Earth.They first began forming about one thousand million years ago.During the millions of years since then，the mountains were changed and reformed by the forces of water and wind.Ice also changed the mountains，making many of them smaller and digging valleys and lakes among them.Many different kinds of trees grow along the trail.And many different kinds of animals live in the forests along the trail.
Lands along the trail are protected by the federal government and by state governments.Some parts are not protected by the government directly.Instead，they are protected by legal agreements with private owners willing to permit people to walk across their property.
Walkers on the Appalachian Trail pass through some of the great valley systems of the mountains.They can look down into these beautiful valleys and see farms and forests stretching across the land for many kilometers.Farmland in the valleys is rich and productive.And some of the great events in American history took place in the valleys.For example，one of the great battles of the American Civil War was fought in the Shenandoah Valley in Virginia.
The Appalachian Trail________.

A．is more than four thousand three hundred kilometers long

B．starts in the northern state of Maine

C．goes through more than fourteen states

D．ends in the southeastern state of Georgia

The Appalachian Mountains________.

A．are the first completed part of the National Trails System

B．began forming one million years ago

C．were changed by natural forces like water，wind and ice

D．were around by valleys and rivers and famous for its scenery

The lands along the trail________.

A．are protected entirely by either the federal government or state governments

B．are mainly protected by legal agreements with private owners

C．can be visited by travelers freely only under the permission of owners

D．are protected by both the federal government and state governments

What is mainly described in the last paragraph?

A．The Appalachian Mountains have some great valley systems.

B．Farms and grasslands stretch across the valleys for many kilometers.

C．One of the American independence battles was fought in the Shenandoah Valley.

D．Lakes in the Appalachian Mountains are one of the most beautiful sights.

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