向澄清石灰水中不断通入CO2气体,下列四个图象中能正确表达其反应进程的是[ ]
A.
B.
C.
D.
答案:C
主动脉球囊反搏(1ABP)辅助期间,维持ACT的最佳值()
A.150~200秒
B.200~250秒
C.>250秒
D.100~150秒
E.<100秒
—Can you describe ______ it happened?
—Yes, I was riding on my bike ______ a car knocked me down from behind.[ ]
A. when; as
B. how; as
C. how; when
D. how; while