1 Are you doing a test? Yes, I am.
2 Is your teacher sleeping? No, she isn't. (или No, he isn't - если учитель - мужчина)
3 Are your friends studying? Yes, they are.
4 Is it raining today? No, it isn't.
5 Are your classmates singing? No, they aren't.
6 Is your dad working? Yes, he is.
**Present Continuous образуется с использованием формы глагола to be (am/is/are) и причастия наст. времени (глагол+ ing).
Нужно помнить, когда используются формы глагола to be:
I am
He/she/it is
We/you/they are