Решение:
Нужно начать вопрос с подходящей формой глагола 'to be' (is, are), учитывая подлежащее.
- Are you in the bathroom? (You — всегда 'are')
- Is your sister in the kitchen? (Your sister — ед. ч., 3-е лицо)
- Are your Mum and Dad in the garden? (Your Mum and Dad — мн. ч.)
- Are your friends in the house? (Your friends — мн. ч.)
- Is your friend in the living room? (Your friend — ед. ч., 3-е лицо)
Ответ: 1. Are, 2. Is, 3. Are, 4. Are, 5. Is.