by day

基本解释

These should be backed up with millions of solar lanterns, which shine by night and recharge by day.
还应该有百万计的太阳能灯提供照明支持，这些灯在晚上发光并在白天再次充电。
Perhaps for two reasons: first, God wants us to lean on him day by day; and second, he knows we can’t handle looking forward to a whole lifetime all in one chunk.
可能出于两个原因：首先，上帝希望我们一天接一天的仰靠他；其次，他知道我们是承受不了那种一下打包得到全部的人生的期望。
They have minimal contact with the local population except on the roads, railways and other projects where they work by day.
他们与当地人接触极少，只有白天在他们工作的马路、铁路和其它项目上打打交道。

By day and night,never stopping, biting at his nose, biting at his feet, the wolves stayed with him until the end.
On day four, The heavenly bodies that give off light by day or night are created.
在第四天，那些在白天或者晚上发光的天体被创造了。
耶鲁公开课 - 旧约导论课程节选
And that's how you make exercise day by day.
你就这样每天练习。
英语学习就要这样 - SpeakingMax英语口语达人

Day by day, Congress is asking more questions about the bailout of the financial industry.
NPR: Senators Skeptical Of Bailout Package