单项选择题 The development goals for a large marine engine are many often interact and in some cases even with each other（）

单项选择题 The key feature of the Sulzer RT-flex system is that it gives complete freedom in the and operation of fuel injection and exhaust valve actuation（）

单项选择题 A clearly visible beneath of RT-flex engines is their operation at all ship speedsThis is achieved by the superior combustion performance（）