题目内容：

语法填空（共 10 小题；每小题 1.5 分，满分 15 分）

Grand Canyon National Park recently turned 100 years old. The1.(nature) wonder in northern Arizona became one of America’s early national parks in 1919. A century later, about 6 million people a year visit the park,2.is about the size of the state of Delaware.

Native tribes (部落) had many names for the huge canyon. But in 1869,3.(explore) John Wesley Powell gave it a name that stuck: the Grand Canyon. The canyon isn’t the world’s longest or deepest. But it surely is grand. It offers beautiful views.

The canyon itself is far4.(old) than the park. No one knows exactly5. old the canyon is. The rocks6.the bottom are about 1.8 billion years old.

Humans first came to the area about 12,000 years ago. They left behind a large number of stone tools. For the past century, tools7.(make) from small sticks8.(find) in some of the canyon’s caves.

Plenty of animals live in the park. Desert bighorn sheep are9.largest animals in the Grand Canyon.10.(measure) 300 pounds, they climb over the rocks. The park is home to almost 375 kinds of birds and a few living things that can be found nowhere else.