His mind would wander, and he would lose track of what he was doing
他会走神，忘了自己正在干什么。
2.in the absence of 没有
In the absence of such evidence, there is no a priori hypothesis to work with.
没有此类证据，就没有可以推理的前提。
3.pay off 成功
Sandra was determined to become a doctor and her persistence paid off.
桑德拉决心成为医生，她的坚持取得了成功。
4.drop off 减少
Sales to the British forces are expected to drop off
预计对英国军队的销售量会减少。
5.sort of a 有几分
He was trying to decide whether the question was some sort of a trap.
他试图判断那个问题是不是个套。
