1.be concerned about 关心;关注
It's a teacher's duty to be concerned about the students'study.
关心学生的学习是教师分内的事
2.a series of 一连串;一系列
The students have put forward a series of questions.
学生们提出了一系列问题
3.under control 在控制中;受到控制
Firemen said they had the blaze under control.
消防队员说他们已经控制住了火势
4.once again 再次;又一次
Once again I breathed as a free man.
我又能像个自由人一样呼吸了