Beef production has fallen nearly fourfold.

牛肉的生产也降了近四倍。

The output of grain increased fourfold.

粮食产量增加了三倍。

The population in this area has increased fourfold.

该地区的人口已增加到四倍。

The method of statistics was exact probabilities in fourfold table.

统计学方法应用四格表确切概率法。

Oil now accounts for 12% of Brazil's GDP, a fourfold increase since 1997.

目前石油占巴西gdp百分之十二，较1997年增加了四倍。