Hxen.com's tips：Every day persisted can learn English well!-->■Learn English Everyday■
aerospace –adj. describing the industry of making vehicles that travel in the atmosphere and in space
customer –n. a person or organization that buys goods and services from businesses
certification –n. the process of gaining official approval to do something like carrying out a business or doing a task
mission –n. a flight or a spacecraft designed to carry out a task
