When you arrive in a country, you clear customs. A lot of countries have two channels: the green channel and the red channel. Some countries, like India, have three channels: the white channel, the green channel and the red channel.
到达一个国家时要通关。许多国家的海关有两种通道:绿色通道和红色通道。还有些国家如印度有三种通道:白色通道、绿色通道和红色通道。