1.a heightened state of 处于高度……的状态
Although it's a precaution, the police force here in the capital Seoul have moved to a heightened state of alert.
尽管只是预防措施，韩国首都首尔的警力已经处于高度戒备状态xE]8-n^P8e。

2.swell into 膨胀至；扩大至
Protests start over fuel price increases, then swell into the largest pro-democracy demonstrations since 1988.
一开始引发抗议的燃油价格的上涨，后来竟发展成为了自从1988年以来规模最大的一次民主示威活动CRdB#_!qe0K)csk。

3.in the back of one's mind 在某人脑海/心灵深处
Sometimes the incident seemed very close, sometimes far away. But always it lurked in the back of my mind.
这种渴望忽远忽近，但始终潜藏在我心灵深处的某个角落-]^.pp]wke。

4.so far this year 今年以来
An earthquake scientist said the shift illustrated the huge force of the tremor, the biggest so far this year.
地震专家表示，这证明了此次地震的威力之大，是今年以来最大一次地震[mwuY4Hf*A|e。