求教一长句翻译

the purifying effect is based on the nitrogen oxides being stored in the form of nitrates by the storage material of the storage catalyst during a lean operating mode of the engine and the previously formed nitrates being decomposed in a subsequent rich operating mode of the engine and the desorbed nitrogen oxides being reacted with the reducing exhaust gas constituents over the storage catalyst to form nitrogen, carbon dioxide and water.

多谢了

我认为只需要加几个标点符号，这个句子就不难了：
the purifying effect is based on:
the nitrogen oxides being stored in the form of nitrates by the storage material of the storage catalyst during a lean operating mode of the engine; and
the previously formed nitrates being decomposed in a subsequent rich operating mode of the engine; and
the desorbed nitrogen oxides being reacted with the reducing exhaust gas constituents over the storage catalyst to form nitrogen, carbon dioxide and water.

能给出完整翻译吗？
断句后翻译出来的话很别扭。不太会翻这种长句 ：（