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