Our population is concentrated in the big cities. 我國人口集中在大城市里。
The oil industry is marked by an element of danger, hence the siting of refineries at a distance from population centres. 石油工業(yè)的特征是它有一點(diǎn)點(diǎn)危險性,所以煉油廠(chǎng)的廠(chǎng)址總在遠離人口集中的地方。