溶洞以及生物洞穴或植物根茎腐烂后形成的孔洞不能造成绕坝渗漏。
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使用脚扣进行登杆作业时,上、下杆的每一步必须使脚扣环完全套入并可靠地扣住电杆,才能移动身体,否则会造成事故。
A. 正确
B. 错误
How dose water enter the crankcase of a diesel engine?（）
A. Through the crankcase exhauster
B. As water vapor contained in blow-by
C. Demulsifying lube oil passing through the main bearings
D. Condensation from vapor formed in the expansion tank
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