A：植物蒸腾失水的“门户”
B：气体交换的“窗口”
C：由一对半月形的细胞围成的空腔
D：白天闭合,晚上张开
—________ is OK. I'm busy today and tomorrow.
— Yes. It is beautiful and has many colours.
下列物质中允许旅客带上列车的是（ ）
