儿童权力的核心是（ ）。
Which statements about MPLS Label Distribution Protocol（LDP） are valid？（） ["LDP hello packets are sent to UDP port 646","LDP hello packets are sent to TCP port 711","LDP sessions are TCP sessions to port 646","LDP sessions are TCP sessions to port 711","LDP establishes a peer relationship with another router that must be directly attached","LDP can establishes a peer relationship with another router that is not directly attached"]
洁净区的设计必须符合相应的洁净度要求，包括达到（）和（）的标准。
污染物进入环境的途径有哪些？
动态指标主要包括（） ["动态投资回收期","净现值","净现值率","内部报酬率"]
何为正常时差？何为倾角时差？各与什么量有关？
