But they are not able to tell exactly where or when a tornado will hit.

VOA: special.2010.05.11

This is actually very representative of when you do research in the laboratory, you will find often things do not work quite exactly as they worked 20 minutes ago when you just checked it in your office, for example.

在实验室做研究时,这个实际上是非常具有代表性的，举个例子,当时只是在办公室核查它时,你经常会发现事物无法,像它们20分钟之前那样精确的工作。

麻省理工公开课 - 化学原理课程节选

But he said he is ready. "I cannot tell you exactly when I will be seated, but I think it will be early next week,"

VOA: standard.2009.06.30

And as for the re-shuffle - when exactly will the Prime Minister choose to shuffle himself out of Downing Street?

BBC: After the reshuffle are the knives still out for Blair?

If the watch really is the future of the "wearable technology" buzz-industry, the question remains about when exactly it will reach mainstream popularity.

BBC: Do we need watches to tell us more than the time?

The first performance was over the weekend, and the museum won't say if there's a schedule for when exactly it will come back for six other performances.

WSJ: The art of the nap: Tilda Swinton at MoMA