Question

passar as sentenças para o plural
- This is an address book
-That is a match
This is a leaf
That is a genteman
This is a baby

Answer 1

These are adress books
Those are matches
These are leaves
Those are gentlemen
These are babies

Answer 2

Fácil, É só seguir este conceito:
Singular- This
Plural- These

Singular-That
Plural- Those

Singular-Is
Plural- Are

Assim, fica mais fácil passar o resto da frase para o plural...

These are adress books
Those are matches
These are leaves (Geralmente, as palavras em inglês terminadas em "f", no plural é trocado o "f" por "v" +  "es")
Those are gentlemen
These are babies

Espero ter ajudado!!!