A.正定矩阵
B.初等矩阵
C.正交矩阵
D.正交矩阵
[判断题]对错A.对B.错
[判断题]A.对B.错
[单选题]A.B.C.D.
[单选题]A.下唇B.上唇C.食指D.拇指
[单选题]A.袋内壁刮治术B.翻瓣术C.隧道成形术D.截根术E.引导性组织再生术