【判断题】单位时间内流体在流动方向上所流过的距离称为流速,以u表示,单位为m/s。
【判断题】在实验室里工作时,要始终穿着实验服,实验室外禁止穿防护服( )
【判断题】单位时间内流体在流动方向上所流过的距离称为流速,以u表示,单位为Kg/m 2 ·s。
【单选题】The latest evidence from ESA's Mars Express, and the NASA rovers show _________.
A.
Mars is thought to be dry and barren
B.
there is liquid water on or near the surface
C.
there used to be life on Mars
D.
Mars might once be warm and wet
【单选题】Under the regulations for cargo vessels,which statement is TRUE concerning fireman’s outfits?()
A.
If a vessel carries two outfits,they may be stored in the same location
B.
Each fireman's outfit shall contain a flame safety lamp of an approved type
C.
Each fireman's outfit shall contain a fresh-air breathing apparatus
【多选题】高压蒸汽灭菌法,水蒸汽的温度超过100度,适合哪些物品的灭菌