小红站在桥上,从桥面向河中扔下一块石头,见落石水花开始记时,经0.2s听到落石击水声,则桥高出水面多少米?
h=v声t=340m/s×0.2s=68m.
答:桥高出水面68m.
Nancy doesn't enjoy her job anymore. She's _________ because every day she doesexactly the same thing. [ ]
A. relaxing
B. relaxed
C. boring
D. bored
建筑工程施工安全技术
起重机械的基本参数中,______是以建筑物尺寸和施工工艺的要求而确定的。
A.起重力矩 B.起升高度C.轨距 D.工作幅度