When How can we figure out that 's' is about possession, and when is 's' a letter not the verb 'is' or even the verb "has"?
Note the last part I added to your question. The basic explanation is:
- If there is a
past participle verb in the part of the clause that follows after the
's, then it is short for "has".
For example:
Tom's truly been much happier after quitting that terrible job. [Tom has truly been much happier after quitting that terrible job.]
-If there is just
a noun phrase (and no other finite verb) in the part of the clause that follows after the
's, then it is short for "is".
For example:
Tom's a happy-go-lucky guy. [
Tom is a happy-go-lucky guy.]
-If there is
an -ing verb in the part of the clause that follows after the
's, then it is short for "is".
For example:
Tom's running fast. [
Tom is running fast.]
-If there is already
a finite verb (indicating tense) in the part of the clause that follows after the
's, then it is the possessive "s".
Tom's persistence paid off in the end. [
The persistence of (the persistence that belongs to) Tom paid off in the end].