booster rocket英 [ˈbuːstə(r) ˈrɒkɪt]美 [ˈbuːstər ˈrɑːkɪt](起飞)助推火箭(发动机)英英释义nounthe first stage of a multistage rocketSynonym:boosterbooster unittakeoff boostertakeoff rocket双语例句