单项选择题 For auxiliary engines the permissible overload is （） for one hour every twelve hours.

单项选择题 The scavenge air receiver is of a simplified and modular design with integral non-return flaps, hanging cooler and two auxiliary air blowers（）

单项选择题 The piston crown employs the usual jet-shaker principle with an arrangement of cooling bores in the crown so that the surface temperatures of the crown are moderate with a very even distribution（）