Early jet engines had narrow inlets and were very noisy, but as the diameter of the fans at the front increased, the engines became quieter.
早期的喷气式发动机进气口狭窄且噪音巨大但是随着前部风扇直径的增大发动机变得越来越安静。
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The new trainers will prepare fast jet aircrew for flying front-line aircraft with a modern cockpit environment of digital displays sophisticated navigation and advanced avionics.