轿厢在两端站平层位置时,轿厢、对重的撞板与缓冲器顶面间的距离,耗能型缓冲器应为().
A.150~350
B.200~350
C.150~400
D.200~400
参考答案:C
现代物理学的两大理论基石是()。
A.牛顿力学和电磁理论
B.粒子和中子学说
C.相对论和量子力学
D.地质力学和相对论
As the sky grew darker, the stars ________ one by one, shining in the distance.[ ]
A. came out
B. came about
C. came on
D. came in