in no time/at no time

意思完全不同。in no time 意思是“马上”“立刻”“一会儿”“很快”“一转眼”：

1. I'll be back in no time. (Wilde) 我马上就回来。

2. With five hungry children seated round the table, the food disappeared in no time. (Wood) 五个饥饿的孩子围坐在桌边，那点儿吃的一会儿就吃光了。

3. The operation was a success and the doctors say she'll recover in no time. 手术很成功,医生们说她很快就会恢复健康。

4. I could make Eric Cobbley's name in no time, and ever so many others. 我可以转眼间就使伊立克·考柏莱成名，也可以使许多别的人成名。

5. In no time we cleared the table. (“We cleared the table within a short time.”) (CGEL) 我们很快就把桌子收拾干净了。

at no time 则表示“从不”“绝不”“在任何情况下都不”：

At no time was war as imminent as now. (“War wasn’t as imminent as now at any previous time.”) (CGEL) 战争从未像现在这样逼在眼前。

注意: at no time 位于句首时主语和谓语要实行部分倒装。