[单选] Water allowed to accumulate in the hydraulic system oil will cause an oxidation process producing by- products which are normally （）.
A . gums, acids, and varnishes B . removed by cellulose type filters C . neutralized by oil additives D . not removed by absorbent filter
冒顶片帮伤人排除方法之一是作业前应敲帮问顶，并及时处理。
简述锚头鱼蚤病的流行情况。
下列哪些特征是管胞所特有的？（） a.细胞壁加厚 b.细胞两端尖斜 c.可输送水分和无机盐 d.是死细胞，其细胞核和细胞质消失 e.具壁孔 f.端壁打通 a，c，d，e，f。 a，b，c，d，f。 b，c，d，e，f。 a，b，c，d，e。
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污泥中的水分大致分为（）类。 A.4。 B.1。 C.2。 D.3。
Water allowed to accumulate in the hydraulic system oil will cause an oxidation process producing by- products which are normally （）.
