问题 问答题

在建立回归趋势预测模型时,如何选择适当形式的趋势方程来进行模拟

答案

参考答案:在建立回归趋势预测模型时,可以用下面两种方式选择适当形式的趋势方程来进行模拟。第一种方法是将时间序列数据描绘在坐标图上,根据数据的变动规律来确定适当形式的趋势方程。但是这种方法不能使我们了解到模型预测误差的大小,所选择的模型应该是预测误差最小的一种。因此,在实际中我们最好还是选择第二种方法,即:首先利用不同的趋势模型对历史上各期的值做出预测,然后计算各个模型预测的误差,从中选择预测误差最小的一个。

阅读理解

One Sunday morning, when I was driving along a road, I saw something I couldn’t believe. A little girl, who was less than two years old, was pushing her stroller (婴儿车) across the road. The traffic was not heavy that morning.

I stopped my car at once and ran toward her. This little girl knew enough to run from a stranger. I tried to catch her in order that I could get her out of the road.

Suddenly her father came running down a hill across the road from where I had parked my car. He ran right to her and caught her up, saying “bad girl” to her. I picked up the stroller and gave it to him. The father grabbed the stroller and walked toward where he came from without a word.

I went back and sat in my car for a few minutes with my son. My hands were shaking and tears were about to run out of my eyes. “Do you feel cold, Mom?” asked my son. I just shook my head.

After this happened, I thought about how thankful I am. Even though the father didn’t say “Thank you”, I feel that I did something good. Doing something for someone else is pleasing, even when it’s only a matter of being in the right place at the right time.

I didn’t really “save” her, but I feel like it was important that I happened to be there. It is sad that I was the only one who stopped. It really made me a little disappointed that no one else stopped to help.

小题1: The little girl ran away from the author because _____.

A.she wanted to look for her father

B.she wanted to stay on the road

C.she needed to catch her stroller

D.she didn’t know the author at all小题2:When the author saw the little girl, _____.

A.there weren’t many cars on the road

B.the girl feared to go across the road

C.the girl had lost her way

D.she was driving to work in a hurry小题3: What can we learn from the passage?

A.The author shared her experience with her son.

B.The author felt sad that no one else helped the girl.

C.The girl’s father didn’t like the girl at all.

D.The girl’s father had wanted to thank the author.小题4:Why were the author’s hands shaking?

A.Because the weather was very cold at that time.

B.Because she failed to be understood by the girl’s father.

C.Because she was not feeling well.

D.Because she was too excited to keep calm.

单项选择题