essential – adj. extremely important and necessary

orbit – v. to travel around (something, such as a planet or moon) in a curved path: to make an orbit around (something)

orbit – n. the curved path that something (such as a moon or satellite) follows as it goes around something else (such as a planet)

certain – adj. not having any doubt about something: convinced or sure

technical – adj. relating to the practical use of machines or science in industry, medicine, etc.
 2/3   首页 上一页 1 2 3 下一页 尾页