3 Complete the sentences as in the example. Long form
Short form
1 L... am... singing.
I'm singing.
2 We
brushing our teeth. ( We
brushing our teeth.
3 He
doing his homework. ♡ He
doing his homework.
4 It
flying. In
It
flying.)
5 They are not... drinking tea. (X) They... aren't... drinking tea. (x)
6 You
sitting. (*)
You
sitting. (
7 She
swimming. )
She
swimming. ~
8 It..
barking. (*)
It
barking. (*)

Начиная с пятого предложения надо в отрицательно форме? Если да, то вот:

1 I am singing.

I'm singing.

2 We are brushing our teeth.

We're brushing our teeth.

3 He is doing his homework.

He's doing his homework.

4 It is flying.  

It's flying.

5 They are not drinking tea.

They aren't drinking tea.  

6 You are not sitting.  

You aren't sitting.  

7 She is not swimming.  

She isn't swimming.  

8 It is not barking.

It isn't barking.

Объяснение:

Полная форма | Краткая форма личныйх местоимений с комплиментарной для них форой глагола "to be":  

I am | I'm

She is | She's

He is | He's

It is | It's

You are | You're

We are | We're

They are | They're