One describes the great precision involved in the operation, saying that "positioning has to start all over if the margin between two blocks exceeds 5 cm." Each block takes about half an hour to fit into place.
「兩塊混凝土塊的落差超過五公分以上，還得重新來過」，一身濕淋淋的陳先生說，安放一塊塊石，平均得半個鐘頭。