卢旺达的人口将增加四倍，达到4200万，这将使它的人口密度达到日本的五倍。
Rwanda's population would rise fourfold, to 42m, giving it a density five times that of Japan.
磁盘介质的存储密度，在这种密度下磁盘的信息存储量是单密度盘的四倍。
The storage density of a disk medium; storing four times the amount of information per disk as single density.
如果人体组织和电极之间的有效接触面积保持不变，那么高频电流强度扩大一倍将会使电流密度增大一倍，并产生四倍的热量。
Doubling hf-current results in a doubling of current density and a fourfold heat provided that the area of effective contact between the tissue ang the electrode remains constant.
应用推荐