单项选择题
A.four-stroke
B.two-stroke
C.slow speed
D.reversible
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 ().
单项选择题 The usual method of effectively applying foam on a fire is by ().