https://online2.tingclass.net/lesson/shi0529/0009/9907/309.mp3
https://image.tingclass.net/statics/js/2012
講解文本：
on the ball 機(jī)靈，聰明能干，機(jī)智
The new clerk is really on the ball. Everyone likes him
新來(lái)的職員真能干，大家都喜歡他。
You can trust Jack. He has a lot on the ball.
你可以相信他，他很有一套。
瘋狂練習(xí)吧!
