Complete the sentences. Wrate.
1. is this ...."s book (ruler /pensil case)? - 
    Yes it is/ No, it isn"t.
2. Whose ...is this? - It"s...  .
3. What color is your...? - It"s...  .

Is this Tom's book? - Yes, it is/No, it isn't.Whose ruler is this? - It's Tom's ruler.What color is your pencil case? - It's green.