社会主义道德建设要坚持以为（）为核心。
参考答案：人民服务
He has ___________ in teaching and ___________.[ ]
A. experiences；a wonderful experience
B. experiences；wonderful experience
C. experience；a wonderful experience
D. experience；wonderful experience
内孔翻边又称（）
A.压缩翻边
B.伸长翻边
C.挤压翻边
D.胀形翻边
