A:点燃蜡烛时,石蜡先熔化后燃烧
B:火焰分为三层
C:罩在火焰上方的烧杯内壁会出现水珠
D:熄灭时产生的白烟为二氧化碳
设函数f(x)=2x-1,x<11x,x≥1则f(f(2))=( )
More and more people prefer ______ in the wild _____in the hotel. Because they want to experience life.