如图甲所示，两个带正电的小球A、B套在一个倾斜的光滑直杆上，两球均可视为点电荷，其中A球固定，带电量Q_A=2×10^﹣4C，B球的质量为m=0.1kg．以A为坐标原点，沿杆向上建立直线坐标系，B球的总势能随位置x的变化规律如图乙中曲线Ⅰ所示，直线Ⅱ为曲线I的渐近线．图中M点离A点距离为6米．（g取10m/s²，静电力恒量k=9.0×10⁹N•m²/C²．）

设偶函数$f\left(x\right)$满足$f\left(x\right)=2^x-4(x\ge 0)$，则$\left\{x\right|f(x-2)>0\}$=（  ）

    When it comes to car hiring,all car hire companies require that you should have a full driving license for at least one year,some of whom may ask for two years,especially for younger drivers.

    Most car hire companies will not automatically hire out a car to someone under the age of 25 or to people over 70. But there are exceptions. Some listed companies are normally prepared to serve people of 21 and over. And some may go over the age limit and provide service for older people( aged 70 and over) providing you have no record of breaking the law and valid license, and a doctor's letter of good health.

    Now read on for some information about national companies with many bases hiring out cars to people aged 21 and older drivers.

根据光合作用的反应式，描述正确的是（　　）

二氧化碳+水 $\underset{叶绿体}{\overset{光能}{\to }}$ 有机物（主要是淀粉）+氧气．