读图，完成下列各题。

绝对值不大于3的所有整数的积等于____ 

依次填入下面横线处的语句，与上下文衔接最恰当的一组是（     ）
但是，就在秦始皇下令修长城的数十年前，四川平原上已经完成了一个了不起的工程。       ，       。       ，       。       ，       。有了它，旱涝无常的四川平原成了天府，每当我们民族有了重大灾难，天府之国总是沉着地提供庇护和濡养。
①长城占据了辽阔的空间
②而它至今还在为无数民众输送汩汩清泉
③它的规模从表面上看远不如长城宏大
④却注定要稳稳当当地造福千年
⑤长城的社会功用早已废弛
⑥它却实实在在地占据了邈远的时间

根据短文内容，选择最佳答案。

    When asked about happiness, we usually think of something extraordinary, an absolute delight, which seems to get rarer as we get older.

    For kids, happiness has a magical quality: Their delight at winning a race or getting a new bike is unreserved (毫不掩饰的).

    In the teenage years, the concept of happiness changes. Suddenly it's conditional on such things as excitement, love and popularity. I can still recall the excitement of being invited to dance with the most attractive boy at the school party.

    In adulthood the things that bring deep joy－love, marriage, birth－also bring responsibility and the risk of loss. For adults, happiness is complicated (复杂的).

    My definition of happiness is “the capacity for enjoyment”. The more we can enjoy what we have, the happier we are. It's easy to overlook(忽视) the pleasure we get from the company of friends, the freedom to live where we please, and even good health.

    I experienced my little moments of pleasure yesterday. First I was overjoyed when I shut the last lunchbox and had the house to myself. Then I spent an uninterrupted morning writing, which I love. When the kids and my husband came home, I enjoyed their noise after the quiet of the day.

    Psychologists tell us that to be happy we need a mix of enjoyable leisure time and satisfying work. I don't think that my grandmother, who raised 14 children，had much of either. She did have a network of close friends and family, and maybe this is what satisfied her most.

    We, however, with so many choices and such pressure to succeed in every area, have turned happiness into one more thing we've got to have. We're so self-conscious about our “right” to it that it's making us miserable. So we chase it and equal it with wealth and success, without noticing that the people who have those things aren't necessarily happier.

    Happiness isn't about what happens to us－it's about how we see what happens to us. It's the skillful way of finding a positive for every negative. It's not wishing for what we don't have, but enjoying what we do possess.

关于某设备的使用年限x和所支出的维修费用y（万元）有如下的统计资料

x	1	2	3	4
y	0.5	1	1.5	3

试用最小二乘法求出y关于x的线性回归方程

参考公式：

用最小二乘法求线性回归方程系数公式： $\hat{b}=\frac{{{\displaystyle \sum }}_{i=1}^n{x}_i{y}_i-n\overline{x}\overline{y}}{{{\displaystyle \sum }}_{i=1}^n{x}_i^2-n{\overline{x}}^2}，\hat{a}=\overline{y}-\hat{b}\overline{x}$ ．