—How long did the meeting last yesterday afternoon? —It was almost supper time______the meeting was over.
A. that
B. until
C. when
D. which
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做现场心肺复苏术前,一般首先检查溺者有无意识。检查必须要在()秒内完成。
A. 2
B. 3
C. 4
D. 5
单人做成人溺者心肺复苏时,吹气的频率应该是()次/分。
A. 20
B. 16
C. 15
D. 12
I wont believe that little boy can run 100 meters in 15 seconds______ I see it with my own eyes.
A. until
B. after
C. when
D. if
游泳时(),容易造成踩踏或撞伤意外事故发生。
A. 水中嬉戏
B. 水中滑行
C. 呛水
D. 打腿