Well we need to put by £200 for the pump valves to be renewed.我们需要存下200英镑以备更换水泵阀。The heart has valves to let blood flow in and out of it.心脏有瓣膜控制血液流进流出.The engineering gang fell earnestly to work on jammed valves.轮机组都起劲地埋...
Limestone is often used in building construction.石灰岩常用于建筑.Cement is made from limestone.水泥是由石灰石制成的.The limestone is sufficiently fissured for tree roots to have breached the roof of the cave.石灰岩上有许多缝隙，故而树根能从岩洞顶部长出来。...