热空气加速老化试验时,将老化箱调至试验温度,把试样呈()状态悬挂在老化箱中进行试验。试样放人老化箱即开始计算()时间,到达规定时间时,取出试样。
参考答案:自由;老化
I could see a whale ________ by a pack of about six other killers. [ ]
A. having been attacked
B. being attacked
C. to be attacked
D. be attacked
下列用电子式表示的形成过程正确的是
A.
B.
C.
D.