Like Chinatoday, most of that pollution was caused by burning coal and, to a lesserextent, by heavy traffic in cities like Los Angeles.

和当今中国一样，当时的污染多由燃煤造成，此外像洛杉矶等城市的大量交通废气排放也是致因。

youdao

Like Chinatoday, most of that pollution was caused by burning coal and, to a lesserextent, by heavy traffic in cities like Los Angeles.

和当今中国一样，当时的污染多由燃煤造成，此外像洛杉矶等城市的大量交通废气排放也是致因。

youdao