clothing optional 直接翻譯是"衣服可以省略","穿不穿衣服都沒關係" 其實就是天體營的意思,像是 clothing optional beach/resort/club 等等
PE in high school should be optional because not everyone enjoys the execrise. Take some for example, their...do their body harm than good. The reason why I think it should be optional is because some people like to run, but others don't like to run...
... depended upon availability, and such parts were often optional. 所使用的樂器要看當時是否備有，而且這樣的零件往往是可有可無的。 2014...