Another brain teaser

[Marie5656]

I can run swiftly and silently when you want me to stay still,

I can move slowly and cautiously and am yours to fill.

You look at me often and yet you always forget me,

I am the most feared killer, yet you can't live without me.

Sometimes you have me for all to spare,

Yet when you need me, I am not there.

You can waste me, or cherish me, you choose the track,

But once you're done you can never get me back.



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TIME

[Sheryl]

I was thinking it was water. :-2

[sunny104]

the answer is at the bottom...:yh_shhhh







:D