【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】The function of the piston rings is to ________.
A.
help cool the piston by transferring heat from the piston to the cylinder wall
B.
provide a sliding seal between the piston and cylinder wall
C.
scrape oil off the cylinder wall as the piston moves down on the power and intake strokes.
【单选题】蔗糖水解动力学实验应注意哪些问题?( )
B.
旋光仪样品管有环状突出部分的一端应向下放置。
【单选题】Piston cooling fins are located
B.
beneath the piston crown
C.
at the base of the piston skirt
D.
inside the cylinder liner cooling water jacket
【单选题】关于肺表面活性物质,下列哪项是正确的
A.
肺表面活性物质在胎龄18~20周时出现,35~36周达肺成熟水平
C.
肺表面活性物质缺乏不是引起新生儿肺透明膜病的主要病因
【单选题】Diesel engine piston ring blow-by is usually caused by excessive ring clearance at the ring___________.