非开挖的通道,应离开地下各种管线及设施足够的_____。
参考答案:安全距离
根据下面提供的情景,写一段接续文字,词数不少于50。
Your grandpa has retired recently. He isn’t used to the idle (闲散的)life and often feels very unhappy and depressed.(压抑的)You are worried about him, so you give him some advice (at least three pieces), trying to make him cheerful. You say to him….
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球团矿成分中列入质量考核的有害杂质一个是(),另一个是()。