69()
A. mean
B. show
C. take
D. have
Nearly half of the ______ (bore) audience had left the meeting before the closing address (闭幕词).
30W紫外线灯一支每照射10~15平方米面积需照射的时间是
A. 10分钟
B. 20分钟
C. 30分钟
D. 40分钟
E. 60分钟
63()
A. preserves
B. protects
C. prevents
D. detects