井筒到底后，应当先短路贯通，形成至少（）个通达地面的安全出口。
A.1
B.3
C.2
参考答案：C
衡量新闻工作者心理是否健康的标准有哪些？
Requirements management is the process of(1),analyzing,tracing,prioritizing and agreeing on requirements and then controlling changes and communicatingto relevant stakeholders.It is a(2) process throughout a project.A requirement is a capability to which a project outcome (product or service) should conform.
空白（2）为（）
A.persistent
B.continuing
C.permanent
D.continuous
