在锻件中可能发现下列哪种缺陷?()
A.未焊透
B.疏松
C.折叠
D.冷隔
参考答案:C
— Where is Ben? — He _____ to the teachers’ office. He will be back soon.
A. go B. has gone C. has been
简述成功的公安组织设计应遵循的要求。