求翻译：3.下坡刹车失灵 ，不能利用车辆本身的机构控制车速时 ，驾驶员应果断地利用天然障碍物 ，如路旁的岩石 、大树等 ，给汽车造成阻力 。如果一时找不到合适的地形 、物体可以利用 ，紧急情况下可将车身的一侧向山边靠拢 ，以摩擦来增加阻力 ，逐渐地降低车速 。是什么意思？

3. downhill brake failure, you cannot use control the speed of the vehicle itself is, the driver should be determined by natural obstacles such as rocks, trees and so next to the road, caused resistance to the car. If you are unable to find suitable terrain, an object, you can use, emergency to close up on a hillside on the side of the body, to increase resistance to friction, reduce speed gradually.