单项选择题 The （） engine is used for alternators and sometimes for main propulsion with a gearbox to provide a propeller of between 90 to 120 rpm.

单项选择题 As for turbine oil, contacting with water in the form of steam will be inevitable so good （） properties will be essential.

单项选择题 Precision engine bearing inserts are manufactured with a small portion of the bearing ends extending beyond the bearing housing or capsThe installation process of these bearings requires sufficient （）.