控制外注式单体液压支柱升柱，承载和降柱的阀组叫（）。
A．安全阀
B．三用阀
C．截止阀
D．控制阀
参考答案：B
She has a pen in one of her hands, but what's that in her _____ hand? [ ]
A. one
B. another
C. the other
D. other
规定汽油的（）％馏出温度是为确保汽油发动机具有良好的加速性和平稳性
A.10
B.50
C.90
D.干点
