The subject that why studies from the specialized subject that studies some major and undergraduate course has jackknife , for instance legal specialized subject and undergraduate course have this kind of case 为什么自考有些专业的专科和本科考的科目有重叠啊，比如法律的专科和本科就有这种情况！
Jackknife of suitable bolster plate is used must not exceed two , total ply must not exceed 15 millimeter , the jackknife of horizontal bolster plate is used must not exceed 3 , thicker bolster plate should be put in lower level 顺垫板重叠使用不得超过两块，总厚度不得超过15毫米，横垫板的重叠使用不得超过三块，较厚垫板应放在下层。
