Allan is visiting Beijing. He needs a m{#blank#}1{#/blank#}of the city. It shows how to travel around the city. Here are the ways of t{#blank#}2{#/blank#}around by bus. Buses go to d{#blank#}3{#/blank#}places in the city. They are cheap, but sometimes crowded. There are a{#blank#}4{#/blank#}double-decker(双层) buses. They are comfortable(舒适) . You can go sight—seeing from the top deck. Here are two ways：One from the east to the west；another round the city like a ring road. The underground trains are fast, b{#blank#}5{#/blank#}very crowded in the rush hours(在繁忙时间) . Taking taxis are fast, but they are rather e{#blank#}6{#/blank#}.