根据《锅炉压力容器焊工考试规则》的规定,Q345(16Mn)钢双面埋弧焊弯曲试样弯曲角度的合格标准为()。
A.180°
B.100°
C.90°
D.50°
参考答案:B
You can never imagine _______difficulty we had _______the cupboard upstairs.
A.what a; to carry
B.how; to carry
C.what; carrying
D.how; in carrying
在再生障碍性贫血的发病机制中,最重要的环节为()。
A.造血干细胞受损
B.造血微环境缺陷
C.免疫机制异常
D.核苷酸代谢异常
E.遗传基因缺陷