1.in addition 另外；此外；加之
例句：In addition, he said, the drug's dosing schedule is only once per month.
此外，这种药物的给药方案只能是每月一次。

2.the absence of 缺乏...
例句：The absence of such a philosophy has been a great failing.
缺乏此类哲学一直是一个重大失败。

3.track down 追捕到；查出；追踪
例句：FBI is trying to track down the hacker.
FBI正在努力追踪黑客。

4.watch over 监视
例句：It is not very effective to watch over our children shoulder to keep an eye on what they are doing in the computer.
当不在孩子身边时，我们无法有效监视他们在电脑上干什么。