功率运行模式下进入反应堆厂房查找缺陷，应从（）开始。
参考答案：辐射水平低的区域
If his parents are convinced _____ the fact that his son always focuses his mind _____ his study.[ ]
A. of; on
B. of; at
C. by; to
D. on; at
钻杆的伤痕疲劳破坏是由于（）而逐步发展的结果。
