单项选择题
A.atop the piston crown
B.beneath the piston crown
C.at the base of the piston skirt
D.inside the cylinder liner cooling water jacket
单项选择题 The ship security assessment is an essential and integral part of the process of developing and updating（）
单项选择题 If a vessel moored at a U-Sterminal does not comply with coast guard pollution prevention regulation, it may be detained by the （）
单项选择题 The temperature of the fuel oil received during bunkering operations is critical in determining the（）