用跟毛皮摩擦过的橡胶棒接触带电的验电器的金属球，发现验电器的金属箔先合拢后又张开，则.（  ）

交通指数是指交通拥堵指数或交通运行指数（Traffic Performance Index，即“TPI”），是反应道路畅通或拥堵的概念性数值，交通指数的取值范围为0～10，分为五级：0～2畅通，2～4为基本畅通，4～6轻度畅通，6～8为中度拥堵，8～10为严重拥堵．高峰时段，巴中市交通指挥中心随机选取了市区40个交通路段，依据交通指数数据绘制的频率分布直方图如图所示：

（Ⅰ）  求出图中x的值，并计算这40个路段中为“中度拥堵”的有多少个？

（Ⅱ） 在我市区的40个交通路段中用分层抽样的方法抽取容量为20的样本．从这个样本路段的“基本畅通”和“严重拥堵”路段中随机选出2个路段，求其中只有一个是“严重拥堵”路段的概率．

阅读理解

    Many people like going shopping at weekends after five days'hard work．Supermarkets are good places for shopping．

    Before you go into the supermarket，get a trolley．Trolleys are usually outside the entrance(入口)．It's good to push your trolley around and take what you want．If you only plan to buy a few things，get a basket．Baskets are usually in the supermarket．You can buy different kinds of things in the supermarket．You can buy fruit and vegetables，meat and fish，bread and cakes，ice cream and magazines．

    There is a big supermarket near my home．My parents like shopping there but my sister Liz and I don't．There'll  be a sale in it on Saturday．My parents are going to buy some carrots and tomatoes．

根据材料内容选择最佳答案。

要使分式$\frac{x+1}{x-2}$有意义，则x的取值是____ ．