竖井已经打下，并且挖有横向矿道。Shafts were sunk, with tunnels dug laterally.空气向下进入竖井,因而失去势能.The air flows down to a shaft and thus loses potential energy.潜水员于上周末进入竖井,但没什么进展.Divers headed into the shafts over the weekend but made little...
to pay your hydro bill付电费In today's practice , a substantial part of hydro - electricity orginates from reservoirs.今天, 很大一部分水电来源于水库.Water power schemes ( hydro - electric schemes ) are of two types, high dams or low...
Photo Gallery: Azurite crystals from Arizona seem to pulse with color.矿物的图片集.蓝铜矿的结晶来自亚利桑那州好像添加彩色.Azurite's brilliant color adds to its popularity in creating semiprecious stones.兰铜矿灿烂的色彩加上它的声望造成准宝石的宝石.Limited compan...