— Why does he look sad?—There are so many problems()
I hate the news,()made us very sad.
I hate the news,()made us very sad.
取得SAD级压力容器设计许可的设计单位和审批人员,必须同时具备A级、C级或D级压力容器设计许可和设计审批资格,才能从事相应级别的压力容器分析设计工作。
SAD照射时,要求必须( )。
源轴距(SAD)是( )。
Recreational shoppers go shopping when they are sad.
— Why does he look sad?—There are so many problems()
—What’s the matter, Tom? You look sad.
—Nothing, I about my parents back home.
正确校准SAD的方法是()。