已知等比数列{a_n}为递增数列，且a₃+a₇=3，a₂•a₈=2，则 （  ）

实现循环经济重要的手段之一是（　　）

      Traffic lights are very important for us. I think you know this. But do you know how they were born?
      Garrett A. Morgan was the father of traffic lights. He was an American. His family was very poor. He left school at the age of 14. He was clever. He always looked for better ways to do things. And he liked to make new things.
      At that time, every American wanted to have a car. The streets were full of cars. The traffic was really bad. “Why not put three lights at each corner ? They should be red_,green_,and yellow，” Morgan said , “ Let them tell cars to go or stop.” He made a timer (定时器)to change the lights.
     So we have traffic lights today .

把不等式组$\left\{\begin{array}{c}x>-1\\ x\le 1\end{array}\right.$的解集表示在数轴上，正确的是(    )

如图所示，有一个可视为质点的质量为m=1kg的小物块，从光滑平台上的A点以v₀=1.8m/s的初速度水平抛出，到达C点时，恰好沿C点的切线方向进入固定在竖直平面内的光滑圆弧轨道，最后小物块无碰撞地滑上紧靠轨道末端D点的足够长的水平传送带．已知传送带上表面与圆弧轨道末端切线相平，传送带沿顺时针方向匀速运行的速度为v=3m/s，小物块与传送带间的动摩擦因数μ=0.5，圆弧轨道的半径为R=2m，C点和圆弧的圆心O点连线与竖直方向的夹角θ=53°，不计空气阻力，重力加速度g=10m/s²，sin 53°=0.8，cos 53°=0.6．试求：