1. to (good/best) advantage (=in a way that shows the best of sth)ad.有效地，出色地，很好地
2. be in the air (=If something is in the air, you feel that it is happening or about to happen)a.存在的，即将出现的
3. be on/off (the) air (= to be broadcasting on the radio or television at the present moment, or to stop broadcasting)v.(电视、收音机等)正在播放节目或停止播放节目
4. be up in the air (= if something is up in the air, no decision has been made about it yet)a.无法做出决定的，悬而未决的
5. be on the alert (for) (= ready to notice and deal with a situation or problem)a.警戒着，随时准备着
