The box contains a necklace. = A necklace is in the box.
The can holds two gallons. = ... has a capacity ...
..
These verbs (contain, hold matter, ...) also reveal their stative character in the above senses by their unacceptability with the progressive : * The box is containing a necklace, etc
Again, exceptional uses of these as "process" verbs may be found; eg:
How much was the tank containing when you last inspected it?
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The above is quoted from a grammar book.
Can anyone tell me when we can use these verbs like contain as process verbs?