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