Resposta:

a) Mum isn't making a cake for Jane's birthday.

Is mum making a cake for Jane's birthday?

b) He wasn't opening the windows

Was he opening the windows?

Oi, espero ajudar!

a) Mum is making a coke for Jane birthday.

NEGATIVA: Mum is not (isn't) making a cake for Jane's birthday.

INTERROGATIVA: Is mum making a cake for Jane's birthday?

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b) He was opening the windows.​

NEGATIVA: He was not (wasn't) opening the windows.

INTERROGATIVA: Was he opening the windows?

• OBS.: Entre parênteses estão as contrações!

Sucesso, bons estudos ;)