concrete beam encasement
1tunnels and underground excavations — ▪ engineering Introduction Great tunnels of the world Great tunnels of the worldhorizontal underground passageway produced by excavation or occasionally by nature s action in dissolving a soluble rock, such as limestone. A vertical opening …
2Pencil — This article is about the handwriting instrument. For other uses, see Pencil (disambiguation). HB graphite pencils A pencil is a …
