题目内容：

Arbor Day: Day of Trees

Nebraska was covered with few trees many years ago. The pioneers had trouble in getting enough to build houses. There was no shade from the sun or wind, and crops (庄稼) didn't grow well in the dry earth. So the idea for Arbor Day formed there.

Fortunately, among those moving into Nebraska in 1854 was J. Sterling Morton. He and his wife were nature lovers, and the home they built in Nebraska was quickly planted with trees and flowers. Morton was a reporter of Nebraska's first newspaper, then he became a member of the Nebraska State Board of Agriculture (农业委员会).

On January 4, 1872, Morton first proposed (提议) a tree-planting holiday to be called "Arbor Day" at a meeting of the State Board of Agriculture. The date was set for April 10, 1872. It was estimated (估计) that more than one million trees were planted in Nebraska on the first Arbor Day.

In the years following the Arbor Day, his ideas spread to Kansas, Tennessee, Minnesota and Ohio. Today all 50 states have their own Day of Trees in keeping with local weather.

Hawaii celebrates it in November, while Alaska in May! More interesting, each state has a special "state tree". The "state tree" for Nebraska is cottonwood, for Alaska is Sitka Spruce.

Arbor Day is of American origin (起源) and the idea has spread widely to other lands where it is observed as the "Greening Week" of Japan, "The New Year's Days of Trees" in Israel, "The tree-loving Week" of Korea, and "The National Festival of Tree Planting" in India. Arbor Day in its various forms is now recognized in more than fifty countries. China spends "Tree-planting Day" on March 12.

We have known a lot about Arbor Day. So we should get into action and ask as many people as possible to gather and recycle paper. Then we can use what we earn from the waste paper to buy a special tree to plant in a park or other public places. It is an act of kindness, a labor of love and a duty as citizens. Anyone can do it.

1.Where did Arbor Day start from?

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2.When did Morton first suggest Arbor Day?

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3.What is Alaska's state tree?

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4.How many countries have recognized Arbor Day?

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5.What is the last paragraph mainly about?

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