Patina · Emergencies

How Strong Is It?

can · should · need to · have to

English has four ways to tell somebody what to do, and they are not equally strong. Can is an option. Have to is an order. Reading the bars down the left side is the whole lesson.

★ the four strengths · ★★ which verbs change for he and she · ★★★ choose the right one

Download the PDF PDF · 2 pages

For the teacher · In class

say a real situation and let students argue the strength. "Your friend has a fever" — should or need to? There is often more than one good answer, which is exactly why the exercise on sheet 2 matches meanings, not situations. Practice the question form on Build It — At the Doctor.

Unit 8 teacher's key (PDF)

★ How strong is it?

Four ways to say what to do. Each one is stronger than the one before it. Tap any line to hear it.

can/ can'tIt is possible.You can take medicine for a headache.You can't drive with a broken leg.
should/ shouldn'tIt is a good idea.You should rest today.You shouldn't go to work today.
need to/ don't need toIt is necessary.You need to see a doctor.She doesn't need to go to the hospital.
have to/ don't have toThere is no choice.You have to call 911.He doesn't have to stay in bed.

★★ Does the verb change?

Two of these verbs never change. Two of them change for he, she, and it.

Never changes

can · should

I can
you can
he can
she can
we can
they can

I should
he should
she should
they should

Changes for he / she / it

need to · have to

I need to
you need to
he needs to
she needs to

I have to
you have to
he has to
she has to

After can and should, never use to. Say "He should rest", not "He should to rest".

He to see a doctor.
She to call 911.
My son stay home.
The doctor help you.

★★★ Which verb says it?

Read the meaning. Choose the verb that says it.

It is possible.
It is a good idea.
It is necessary.
There is no choice.
It is not possible.
It is a bad idea.

Careful: don't have to means it is not necessary. It does NOT mean it is forbidden. For forbidden, say can't.