l*******5
发帖数: 2 | 1 Suppose you are a hiker in a mountainous terrain, the mountains being quite
pronounced but smooth, not craggy.
You look for a place to pitch a tent for the night. Now, one can have
torrential rains during the night and then the water assembles into brooks
and streams. Putting a tent where a stream will assemble can be deadly as
you can be washed out and killed.
So you would like to avoid the "stream lines". Intuitively, it is QUITE
CLEAR where these lines pass. They are not everywhere, just so |
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