[MMM]

This is why I'm asking.......

One of the uses for de can be.........

It is placed after a quantity, time or amount of money, and indicates an extent.


This is what I have for uses of de.......


1.Refers to being in an area for a temporary period of time.
2.Is used in regards to location (being at a place).
3.Indicates where an action takes place (can be translated into "in", "at", "on")
4.Indicates means or method of

5.As said above.......It is placed after a quantity, time or amount of money, and indicates an extent.

6.(this is the part I'm having trouble with, and I'm unsure if I'm right or wrong with the use of "de" here) is used to indicate the total cost of something

7.Indicates what an object is made of

This is the use I have for "ni" as a particle....

1.Usually refers to direction (in the process of going somewhere rather
than actually being somewhere)

2.refers to being at a place permanently (such as where you live)
3.refers to when something happens (a point in time; ex:I ate lunch at three p.m.)

4.Is used when a motion or action is directed at or onto an object (direct contact); which of course is about as clear as mud because I have no clue
what a direct object or an indirect object is (nor do I know what a subject
or a predicate is)

5.Is used with frequency expressions (per hour, per day, per person, etc.)


6.Is used to refer to location of existence (where something is located; I believe this is more general than if "de" were to be used in this regards.....is this right or wrong?)
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These seem pretty much right to me.

In terms of the last question, you are correct

McDonald's DE taberu (I eat AT McDonald's)

You can't say "McDonald's NI taberu" because "taberu" isn't a verb that is about coming, going or being.