液压支架的承载过程是指支架与顶板之间相互力学作用的过程。它包括()、()和()三个阶段。
参考答案:初撑;承载增阻;恒阻
In July, 2012, the 30th Olympic Games _____ in London. [ ]
A. will be held
B. be held
C. is held
D. was held
心脏的四个腔中壁最厚的是( )
A.左心室
B.左心房
C.右心室
D.右心房