Isso é muito variável...

Frases no presente que uso os sujeitos ( i,you,we,they) não sofrem flexão no verbo, porém a terceira pessoa que é (he,she,It) sofre flexão no verbo. A 3 pessoa podem sofrem flexão de (s), (es) e (IES) no final do verbo. Segue exemplos.

Verbo to study

I study

You study

He studies

She studies

It studies

We study

You study

They study

Verbo to Wash

I Wash

You Wash

He washes

She washes

It washes

We Wash

You Wash

They wash

Quanto abreviação acredito que você esteja falando do verbo to be..

I am – I’m

You are – You’re

He is – He’s

She is – She’s

It is – It’s

We are – We’re

You are – You’re

They are – They’re