调整图像应先调整什么？（）
A.颜色
B.层次
C.饱和度
D.亮度
参考答案：B
To his surprise, the lifestyle he was used to ______ greatly in the past few years.
A．change
B．changing
C．changed
D．has changed
AHG－4型氧气呼吸器主要部件有哪些？
