跟踪: follow the tracks of; tail after; following; follow-up tracing; track; tracking; trail; lock-on; shadow sb.: 雪地跟踪 follow sb.'s tracks in the snow; 跟踪嫌疑犯 tail after a suspect; 跟踪敌舰 shadow t
空中: in the sky; in the air; aerial; overhead; midair 短语和例子在空中翻筋斗 make a somersault in midair; 在大战期间伦敦受到来自空中的袭击。 during the great war london was attacked from the air. 首次在空中航行的飞行器是气球。 the first
