Routine maintenance on a Central Control Room hermetically sealed air conditioning unit sh

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Routine maintenance on a Central Control Room hermetically sealed air conditioning unit should include _________.

A.changing the air filter

B.recharging the system

C.changing compressor lubricant

D.renewing container vacuum

请帮忙给出正确答案和分析,谢谢!

热搜:a是b的充分条件,b是a的必要条件吗