roller coaster 过山车
随着各种大型嘉年华（carnival）活动的陆续推出，我们有必要对里面的一些游乐设施有所了解，
今天了解的是：
roller coaster
过山车
A steep, sharply curving elevated railway with small open passenger cars that is operated at high speeds as a ride, especially in an amusement park.
翻滚过山车, 云霄飞车：一种上有敞篷的小型车厢且快速行驶的有急转弯的大坡度高架轨道，尤指游乐园中的乘坐装置