患者完成锁骨下静脉穿刺后发生气急、发绀、呼吸音减弱可能有（）
A.导管堵塞
B.感染
C.气胸
D.肺炎
E.输液过多
参考答案：C
污水处理中（）是常见的化学沉淀法。
A、氢氧化物沉淀法
B、硫化物沉淀法
C、碳酸盐沉淀法
D、前三项都是
The country life we ______. The differences between rural and urban areas are disappearing.
A．were used to have changed
B．used to change
C．used to changing
D．were used to has changed
