keep them surprised 意为突然袭击，偷袭
keep them pain down 意为压制。
再送你几个：
Roger that/Affirmtive 明白/了解
Negative（Over not） 不可能
Enemy Spotted 有敌情
Sector Clear/Area Clear 地区无异常
Good job/Nice shot/excellent 漂亮
Keep It Going 坚持到底
Follow Me 跟我来
Cover Me/Need Assistance 呼叫支援
A Site B Site A点/B点集合
Team Hold Position 防守
Stick together team 全体集合!
Storm The Front 突破