为什么要给本来略显笨重的挖掘机增加负担呢?难道不费油吗?首先,挖掘机屁股上的这块铁叫做配重,当然有些是混凝土 经常破碎作业打炮锤容易伤挖掘机吗? 经常听老师傅讲,频繁打炮锤很伤挖掘机,工地上配液压锤的都是旧机器。很多新手可能 【单选题】When she heard of her failure in the experiment her eyes tears whether it was of shame frustration or grief was difficult to tell A were filled with