Answer:
Possibly because if something stained the wall, then it would not come off, would be hard to get off, or will not come off for a long time.
The only thing not mentioned above is:
<span>b.Tax citizens
Levy war means start war, conclude peace is mentioned, and commerce means trading and selling.
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A word that names a group of things is a noun isn't it? Because a noun is a person place or thing.