飞机氧气系统可分为（）供氧系统。
A、正常、应急
B、机内、机外
C、机组、旅客
D、高压、低压
参考答案：C
I’ll never forget our English teacher, _________ is a well-educated teacher, _________ we admire very much.
A．that; that
B．who; it
C．whom; this
D．who; one
征收土地是一种( )行为。
A．法律
B．国家
C．政府
D．集体
