三用阀控制外注式单体液压支柱的（）三个动作。
A、升柱、承柱、降柱
B、支护、卸载、降柱
C、升柱、承载、放液
参考答案：A
He gave his life to ________ Chinese soldiers.[ ]
A. help
B. helping
C. for helping
D. helps
One of the most convenient ways to _____ a city is by taxi.[ ]
A. get off
B. get up
C. get around
D. get on
