家用电冰箱（雪柜）一般使用哪一种制冷剂（）
A. R-507
B. R134a
C. R22
D. R-717
关键指标中要求生产预算成本完成率基准值为（）
A. 96%
B. 90%
C. 85%
D. 80%
“临时绿色许可证”输入允许在越过出站（或发车进路）信号机（）m内停车状态下办理，输入临时的绿色许可证后监控模式立即按关闭信号进行控制。
A. 20
B. 30
C. 45
D. 50
The use of sinking and dispersing chemical agents for removal of surface oil is（）.
A. the most common method used in the United States
B. too expensive for common use
C. generally safe to sea life
D. authorized only with prior approval of the Federal On-Scene Coordinator
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