Past tense ...でする vs. past tense copula です　confusion


Maybe this is a stupid question, because very likely it is possible for
advanced learners to distuiguish this. However, in the present tense ...でする
(particle で) and ...です (copula) are distinct, while in the past tense they
sound the same.

My current way to cope with this problem is to search in e.g. Google for
expressions using the present tense, i.e. either です or で+する and compairing the
number of found pages.

[code]

    Example phrase: 思い出でした
    
[/code]

Google hits for

[code]

    思い出でする: 22
    思い出です: 2.7 million
    
[/code]

Clearly, copula wins over the other "possibility". This is rather awkward.
Especially if there are terms that are less frequently used so Google returns
either way few pages. Is there an easier way I am not seeing?

Thanks!




思い出でする means "to do something as(because of) a memory", this で is a
postpositional particle that is used for "cause", "reason". For example,
彼女と初デートの場所でキスを思い出でしたい.

思い出です means "Something is a memory", です is a copula.

思い出でした can mean the both meanings. For example, 彼女と初デートの場所で、キスを思い出でした(I kissed
my girl friend at the our first date place as a memory),
彼女とのファーストキスは、良い思い出でした(My first kiss with my girl friend was a good memory).




思い出でする means "to do something as(because of) a memory", this で is a
postpositional particle that is used for "cause", "reason". For example,
彼女と初デートの場所でキスを思い出でしたい.

思い出です means "Something is a memory", です is a copula.

思い出でした can mean the both meanings. For example, 彼女と初デートの場所で、キスを思い出でした(I kissed
my girl friend at the our first date place as a memory),
彼女とのファーストキスは、良い思い出でした(My first kiss with my girl friend was a good memory).

