roll·er coast·er
noun/ˈrəʊlə kəʊstə(r)/
/ˈrəʊlər kəʊstər/
- a track at a fairground that goes up and down very steep slopes and that people ride on in a small train for fun and excitement
（游乐场的）过山车，云霄飞车 - a roller-coaster ride
乘坐过山车
- a roller-coaster ride
- a situation that keeps changing very quickly
不断变化的局势 - The last few weeks have been a real roller coaster.
过去的几个星期，形势真是变幻莫测。 - an emotional roller coaster
情绪时好时坏
- The last few weeks have been a real roller coaster.