单项选择题 The ignition quality of a fuel oil is an important operational consideration because it（）

单项选择题 On a large low-speed main propulsion diesel engine, lower main bearing wear is usually measured by using a/an （）

单项选择题 To determine the main bearing clearance of a propulsion diesel engine, you should measure the main bearing shell using a ball anvil outside micrometer and measure the crankshaft journal using a/an （）