—What were you doing when the telephone rang?

—I ______ away my books and ______ to bed.

A．had just put;was going

B．was just putting;went

C．just put;had gone

D．have just put;gone

为什么下沉气流在雷暴的成熟阶段是危险的？（）

A.下沉气流由于降水使其更冷而使得下沉速度加大

B.下沉气流冲击地面后汇集于雷暴云底的中心

C.下沉气流变得比周围大气更暖，并在到达这地面之前转变成上升气流