已知x，y满足$\left\{\begin{array}{c}x\ge 1\\ x+y\le 4\\ ax+by+c\le 0\end{array}\right.$, 且目标函数z=2x+y的最大值为7，最小值为１，则$\frac{a+b+c}{a}=$（　　）

    ____crowd of more than 22,000 people gathered near Las Vegas' famous Mandalay Bay Hotel____the Route 91 Harvest Festival. Without____(expect), from the hotel's 32^nd floor, a gunman opened fire on the people below,____ (kill)59 people and at least 500 injured. It was the most____(dead)shooting in US history. President Donald Trump described____as “an act of pure evil”. He ordered US flags to be____(fly)at half-staff to honor those____died. “In moments of tragedy and horror, America comes together as one. And it always ____(have),” Trump said____(Politician) around the world offered their support for the United States.

2017年是内蒙古自治区成立70周年，近年来内蒙古自治区经济高速增长。根据下列材料，结合所学知识，回答问题。

材料一：内蒙古呼和浩特、包头等周边区域有煤、天然气、稀土、铁、铅锌等数十种矿产资源，其中稀土储量占世界一半，天然气、煤炭储量在全国各省级行政区中均名列前茅。

材料二：右图所示

材料三：稀土行业是内蒙古的重要行业，但长期以来，稀土产品一直以原料型产品为主，稀土深加工技术一直远落后于欧、美、日等发达国家。与此相随的是稀土的乱采滥挖、产业无序发展、环境破坏严重、产品廉价出口等一系列问题。