What are Modal Verbs?
Modal verbs are special verbs which behave very irregularly in English. They are very common and thus you should pay attention to them.
Here are some important differences:
1. Modal verbs do not take "-s" in the third person.
Examples:
He can speak English fluently.
Mike should be here by now. I wonder what's going on. He's always on time.
2. You use "not" to make modal verbs negative, even in Simple Present and Simple Past.
Examples:
She should not (shouldn't) leave without asking her boss.
They may not go on holiday this year.
3. Many modal verbs cannot be used in the past tenses or the future tenses.
Examples:
He will can come with us. It is Not Correct.
She musted study very hard. It is Not Correct.
You should you an equivalent instead:
CAN = BE ABLE TO
He will be able to come with us.
MUST = TO HAVE TO
You had to study very hard.
4. Modal verbs have no infinitives or participles. Instead we use other expressions like " be able to, be allowed to, have to".
Examples:
He is not allowed to tell you this.
I will not (won't) be able to come to work tomorrow.
Here are the most common Modal Verbs and their uses: