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【简答题】

President Barack Obama shouldn't be surprised if his approval rating among students has plummeted
(陡然变差). In a recent speech about US education, he called for extending the school day and year.
The challenges of a new century demand more time in the classroom. Why more time? Because US
students are falling behind students in other countries, he said.
More school
US schools need to lengthen school days and the school year. If we intend to stay competitive with
the rest of the world on test scores and in the job market, we need to add classroom hours and get rid
of summer break almost entirely. As President Obama said, South Korean students spend more than a
month longer in school-and achieve better results than us.
The current twoterm school year and the school days that form it were developed based on an old
system of agriculture. The long summer break allowed children to be home to help tend the fields. It is
not necessary anymore. It may not be popular to cut summer break or extend school days, but that's the
only way to improve US education and get back the American jobs lost to foreign countries.
Home Time
Adding school hours won't solve the problems with our school system. The USA is different from
other countries. US families have full schedules, with participation in sports, community groups, and other
interests. In places such as South Korea, where only several hours of a day aren't spent on school
work, children don't have time to participate in many of those activities.
Giving kids time outside of school allows them to grow in other areas. That's just as important as
learning fractions (分数). Fingers shouldn't be pointed at the school year for being too short, but at
teachers and schools that don't challenge their students and just pass kids along to the next grade. We
do need to hold ourselves accountable for an education system falling behind other countries, but we
also need a solution that actually works.
TitleShould School Hours Be 1. ________
Barack Obama's ideas arouse a
2. ____ US students need 3. ________time to keep up with students in other
countries.
Different opinions4. _ __
viewsTo keep 5. ________in the world and in the job
market;
The long summer break is 6. ________;
Adding school hours is the only 7. ________to
improve US education.

Objectors'
viewsAdding school hours isn't a 8. ______to the
problems with the school system;
Giving kids enough 9. ________time allows
them to grow in other areas;
What actually needs to be done is to
10. ________the current education system.

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题目标签:变差分数
参考答案:
参考解析:
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举一反三

【多选题】剩余变差是指

A.
随机因素影响所引起的被解释变量的变差
B.
解释变量变动所引起的被解释变量的变差
C.
被解释变量的变差中,回归方程不能做出解释的部分
D.
被解释变量的总变差与回归平方和之差
E.
被解释变量的实际值与回归值的离差平方和

【多选题】回归变差(或回归平方和)是指()。

A.
被解释变量的实际值与平均值的离差平方和
B.
被解释变量的回归值与平均值的离差平方和
C.
被解释变量的总变差与剩余变差之差
D.
解释变量变动所引起的被解释变量的变差
E.
随机因素影响所引起的被解释变量的变差