Lemons (to be) sweet? short answer (no)
Are lemons sweet? No, they are not. / No, they aren't.
Amy (to be) 5 years old?
Is Amy 5 years old?
Europe and Africa (to be) continents.
are
He (to be) married? short answer (no)
Is he married? No, he isn't.
Your classmates (to be) friendly? Short answer (yes)
Are your classmates friendly? Yes, they are.
They (not to be) thirsty, they (to be) hungry.
are not/aren't....are
It (to be) cold today.
is
An elephant (to be) a big animal.
is
You (to be) interested in football? short answer (yes)
Are you interested in football? Yes, I am.
Mice (not to be) big animals.
are not/aren't
Washington (to be) in America.
is
This exercise (not to be) difficult.
is not/isn't
I (not to be) a teacher. I (to be) a student.
am not/ 'm not....am
She (to be) very tired.
is
Dogs (to be) man's best friend.
are
Hockey (not to be) a slow game. It (to be) fast.
is not/isn't....is
Mr and Mrs Jones (to be) teachers.
are