Common mistake: “I must to clean my room.” — Correct: “I must clean my room.”
We use 'must' for a strong duty or obligation we feel ourselves; must + the base verb. Note: 'mustn't' means it is prohibited.
must — obligation
Form
Example
Affirmative (duty)
I must clean my room
Negative (prohibition)
You mustn't be late
Question
Must I do it now?
Short answer
Yes, you must.
clean my bedroom — limpiar mi cuarto
take out the garbage — sacar la basura
wash the dishes — lavar los platos
make the bed — tender la cama
tidy up — ordenar
do the laundry — lavar la ropa
water the plants — regar las plantas
feed the dog — alimentar al perro
I must clean my bedroom and take out the garbage.
Sofía must wash the dishes and feed the dog tonight.
You mustn't leave the door open.
Children mustn't play near the stove.
Must I do it now? What must we do before dinner?
Must Ben tidy up his room today?
Must I clean my room? Yes, you must.
Must I go right now? No, you don't have to.
Practice
I ___ clean my room before I go out. (must, must to, musts)
After 'must', we use the base verb without 'to'.
It's Monday. I must take out the ___.
There are clothes on the floor. I must put them ___ the wardrobe.
The books are on the bed. I must put them ___ the shelf.
Find the mistake: I must to wash the dishes.
Unscramble: must, You, your, tidy, desk, .
I make my bed. — Add obligation with 'must'.
What must you do at home every day? (Use 'must'.)
Listening
Abuela Carmen: Sofía, before you go out, you must clean your room.
Sofía: Yes, Abuela. I must make my bed and tidy up.
Abuela Carmen: And the dog?
Sofía: I must feed him too. Must I do the dishes now?
Abuela Carmen: No, you don't have to. But you mustn't forget the plants!
Sofía: Okay, I must water them. So much to do!
Reading
In Abuela Carmen's house, everyone has duties. 'We must respect each other,' she always says. Sofía must clean her room and feed the dog. Her cousin must wash the dishes and water the plants. 'And you, Abuela?' asks Sofía. Carmen laughs: 'I must give the orders! But you mustn't be late for dinner — that is the most important rule.'