( )不是奥氏体不锈钢焊接时防止热裂纹的措施。
A.严格限制焊缝中硫、磷等杂质的质量分数
B.选用双相组织的焊条
C.采用小热输入,多层多道焊
D.选用酸性焊条
参考答案:D
Wow! There are so many books. I really can't decide _____. [ ]
A. where to buy
B. which to buy
C. what to buy
D. how to buy
保护受试者自主权的根本措施是()
A.宣传教育
B.知情同意
C.领导支持
D.承诺福利
E.保护隐私