求翻译：下午，还要去学校参加离退休老师的合唱队唱歌，上两次我们都没参加。唱歌也是一次联络，一次锻炼，至少是对肺合量的锻炼。因此，有人说，没事就把歌来唱，炼炼肺合量。是什么意思？

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This afternoon, but also to retired school teachers chorus sing, the last two times we did not participate in. Singing is also a liaison, exercise at a time, at least on Lung volume training. Therefore, it was stated that, having nothing to sing songs, refining and smelting of lung volume.