Rule1: When a verb ends with sh, ch, ss, s, o or x we add -es to the third person singular. When this is done, the syllable of the word increases by one.
Examples:
I crush
You crush
He/she/it crushes
They crush
We crush
They crush
I fetch
You fetch
He/she/it fetches
They fetch
We fetch
They fetch
Rule 2: When a verb ends with “y” preceded by a consonant, we delete the “y” and add -ies to the third person singular.
Examples:
I cry
You cry
He/she/it cries
They cry
We cry
They cry
I rely
You rely
He/she/it relies
They rely
We rely
They rely
Rule 3: When a verb ends with “y” preceded by a vowel, we simply add -s to the third person singular.
Examples:
I buy
You buy
He/she buys
They buy
We buy
They buy
Rule 4: Apart from the rules above, if the verb ends with any other letter, simply add -s to the third person singular.
Examples:
I laugh
You laugh
He/she laughs
They laugh
We laugh
They laugh