辛亥革命的最后失败给中国人民留下的深刻教训是(        )
①帝国主义、封建主义是中国革命最主要、最凶恶的敌人②民族资产阶级没有力量领导中国民主革命取得胜利③革命要取得胜利必须发动和依靠群众④在半殖民地半封建社会的中国，走资本主义共和国的道路是行不通的

    It was a village in India. The people were poor. However, they were happy. After all, their forefathers (祖先) had lived in the same way for centuries (世纪).

    Then one day, some visitors from the city arrived. They told the villagers there were some people who liked to eat frogs' legs. However, they did not have enough frogs of their own, so they wanted to buy frogs from other places.

    This seemed like money for nothing. There were millions of frogs in the fields around, and they were no use to the villagers. All they had to do was to catch them. They reached an agreement and people sent their children into the fields to catch frogs. Every week a truck (卡车) arrived to collect the frogs and give them the money. For the first time, the people could dream of a better future, but the dream didn't last (持续) long.

    It was not easy to notice (觉察到) the change at first, but it seemed like the crops (庄稼) were not doing so well. It was more worrying that the children fell ill more often, and there seemed to be more insects (虫) around lately.

    The villagers decided that they couldn't just wait to see the crops failing and the children getting weak. They would have to use the money got to buy pesticides (杀虫剂) and medicines. Soon there was no money left.

    Then the people found out the problem. It was the frog. They were not useless. They had been doing an important job—eating insects. Now with so many frogs killed, the insects were increasing (增加) more quickly. They were eating the crops and spreading diseases (传播疾病).

    Now, the people are still poor. But in the evenings they sit in the village square and listen to sounds of insects and frogs. These sounds of the night now have a much deeper meaning.

（Ⅰ）由折线图可以看出，可用线性回归模型拟合月度市场占有率y与月份代码x之间的关系．求y关于x的线性回归方程，并预测M公司2017年4月份的市场占有率；

（Ⅱ）为进一步扩大市场，公司拟再采购一批单车．现有采购成本分别为1000元/辆和1200元/辆的A、B两款车型可供选择，按规定每辆单车最多使用4年，但由于多种原因（如骑行频率等）会导致车辆报废年限各不相同．考虑到公司运营的经济效益，该公司决定先对两款车型的单车各100辆进行科学模拟测试，得到两款单车使用寿命频数表如下：

经测算，平均每辆单车每年可以带来收入500元．不考虑除采购成本之外的其他成本，假设每辆单车的使用寿命都是整数年，且以频率作为每辆单车使用寿命的概率．如果你是M公司的负责人，以每辆单车产生利润的期望值为决策依据，你会选择采购哪款车型？

参考数据：， ${\displaystyle \sum }_{i=1}^6\left(x_i-\overline{x}\right)\left(y_i-\overline{y}\right)=35$ ， ${\displaystyle \sum }_{i=1}^6{\left(x_i-\overline{x}\right)}^2$ =17.5．

参考公式：

回归直线方程为 $\hat{y}=\hat{b}x+\hat{a}$ 其中 $\widehat{b}$ = $\frac{{{\displaystyle \sum }}_{i=1}^n\left(x_i-\overline{x}\right)\left(y_i-\overline{y}\right)}{{{\displaystyle \sum }}_{i=1}^n{(x_i-\overline{x})}^2}$ ， $\widehat{a}$ = $\widehat{y}$ ﹣ $\widehat{b}\overline{t}$ ．