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。...
Many of them are low coral or limestone hideaways of palm trees, trade winds, and sand.许多岛屿是低矮的珊瑚,或隐匿着棕榈树, 信风, 和白沙的石灰石....a rich and deep vein of limestone.储量丰富的深层石灰石矿脉The channel is overlain by siltstone and lenticular ...
很多人认为十三是个不吉利的数字.Many people think thirteen is an evil number.星期五被认为是不吉利的日子.Friday is believed to be an unluckyday.有些人认为透过玻璃看新月是不吉利的。Some people think it is unlucky to look at a new moon through glass....