The delays in certification have also hurt the airline, which is now set to enter the market at a tough time, says Keith McMullan of Aviation Economics, a consultancy.是什么意思_The delays in certification have also hurt the airline, which is now set to enter the market at a tough time, says Keith McMullan of Aviation Economics, a consultancy.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句