液压支架有哪些技术指标?
参考答案:
(1)支架形式
(2)支架高度
(3)支架支撑力
(4)支架工作阻力
(5)支架中心距
(6)泵站供液压力
(7)支架支护强度
(8)重量
His father often tells him _______ in that river because it’s dangerous.
A.not to swim
B.not swim
C.swim
D.to swim