设计文件格式有多种，但每种设计文件上都有（）和（），装配图、接线图等设计文件还有（）。
参考答案：主标题栏；登记栏；明细栏
Some students were late for class because they had been _________ by the heavy storm.
A．kept
B．stopped
C．slowed
D．delayed
6~35kV交联聚乙烯电缆有（）结构。
A.单芯
B.多芯
C.单芯和三芯
