In fact, it's not unusual for a Web 2.0 application to release new features several times a day. (Hence the notion of the perpetual beta.)
事实上，Web 2.0应用程序在一天内发布若干次新功能的情况十分常见(因此有了永久测试版的说法)。
2
Underground, where there is no externally produced day, but only perpetual darkness, it would e artificial lighting that produces the day and this could be adjusted to suit man's convenience.
在地下，没有外界生成的白天，而只有永恒的黑暗，人工照明形成白昼，这就可以根据人的需要加以调整。
3
The pound and a half of sundried salmon, which was his ration for each day, seemed to go nowhere. He never had enough, and suffered from perpetual hunger pangs.