A full-flow 50μm filter is installed ,（） so the injection system components on the main engine are safeguarded.

单项选择题The fuel from the bunker tanks must be treated by before entering the service tanks（）, from where the fuel enters（）

A.centrifugal separators; the engine cylinder
B.oily water separators; the engine cylinder
C.oily water separators; the fuel supply system
D.centrifuges; the fuel supply system

单项选择题When the heavy fuel oil is heated to achieve the viscosity of 10-15 cst, may occur.To avoid this, a system is used in most occasions（）

A.boiling and cavitations; low temperature
B.boiling and cavitations; pressurized
C.leaking and boiling; low temperature
D.leaking and boiling; pressurized

单项选择题In order to improve the working conditions of the crosshead bearings, the bearing pressure is made and the peripheral speed is made in later designs（）

A.smaller, higher
B.higher, smaller
C.smaller, smaller
D.higher, higher

单项选择题In order to control thermal stresses, some types of modern engines use pistons with（）

A.heavy wall and intensive cooling
B.heavy wall and no cooling
C.thin wall and no cooling
D.thin wall and intensive cooling

单项选择题In order to keep the oil film on the cylinder liner during the running-in period, the piston rings are slightly rounded（）

A.on both the external and internal top edges
B.on both the external top and bottom edges
C.on both the external and internal bottom edges
D.on all the four edges