Make questions. This is my umbrella. Is this my umbrella? What is this? 1) This is your scarf. _____ this your scarf? 2) That is my sister. _____ that my sister? 3) These are my friends. _____ these my friends? 4) These are his brothers. _____ these his brothers? 5) Those are pigeons. _____ those pigeons? What is this?

1. This is your scarf. Is this your scarf?
2. That is my sister. Is that my sister?
3. These are my friends. Are these my friends?
4. These are his brothers. Are these his brothers?
5. Those are pigeons. Are those pigeons?

В утвердительных предложениях с глаголом to be is используется с единственным числом, а are — с множественным. В вопросе глагол ставится перед подлежащим.