请简述决策树分析的步骤。

阅读理解。

     Do you know Eskimos? Let me tell you something about their lives.

     Eskimos live near the North Pole (北极). There are only two seasons there, winter and summer.

     There is no spring or autumn there. The winter nights are long. You can't see the sun for more than

two months, even at midday. The summer days are long. For more than two months, the sun never goes

down and there's no night.

     Eskimos have warm clothes. They make their clothes from the skins of animals. From skins (皮毛)

they make coats, caps and shoes.

      Near the North Pole trees can't grow, for it is too cold there. The Eskimos have to make their houses

from skins, snow or stone. When they got out in storms and can't get back home, they make houses of snow.

They leave these houses when the storm is over.

     Life is hard for the Eskimos, but they still like to live there.

1.Near the North Pole there are _____ in a year. [ ]

A. two seasons - winter and summer

B. two seasons - spring and autumn

C. four seasons

D. two seasons sometimes and four seasons sometimes

2.How long does the longest day or night last (持续) near the North Pole? [ ]

A. 24 hours

B. Over a week

C. A month

D. Over two months

3.Eskimos use skins to make _____. [ ]

A. clothes

B. houses

C. trees

D. both A and B

4.There are no _____ near the North Pole. [ ]

A. days

B. nights

C. trees

D. animals

5.Eskimos make houses of snow to protect (保护) themselves from _____. [ ]

A. animals

B. storms

C. snow

D. rain

从菜豆种子与玉米种子的结构来看，前者有______片子叶，后者有______片子叶．

下图是2011年12月出版的一本新书的封面。此书出版意在纪念的历史事件是

A．洋务运动

B．戊戌变法

C．新文化运动

D．辛亥革命

昆曲江河日下开始于（）。

A.清朝前期

B.清朝中叶

C.清朝晚期

D.民国年间