【单选题】关于肺表面活性物质,下列哪项是正确的( )。
A.
肺表面活性物质缺乏不是引起新生儿肺透明膜病的主要原因
D.
肺表面活性物质在胎龄24周时出现,35周迅速增加
【单选题】An axial piston pump differs from a radial piston pump as the pistons of an axial piston pump are positioned _____.
A.
radially from the shaft
B.
parallel to each other and to the shaft
C.
parallel to each other but at a right angle to the shaft
D.
at an angle to each other and to the shaft
【单选题】关于肺表面活性物质,下列哪项是正确的( )
A.
肺表面活性物质缺乏不是引起新生儿肺透明膜病的主要原因
D.
肺表面活性物质在胎龄18-20周时开始产生,35~36周达肺成熟水平
【多选题】在进行沉淀的操作中,属于形成晶形沉淀的操作有
【简答题】Engine is the power source of the automobile. Power is produced by the linear motion of a piston in a cylinder. 英译汉:
【单选题】A separate piston cooling system is used _____ any contamination from piston cooling glands to the piston cooling system only.