The equivalents of the modal verbs.

Tense

Modal verb

Equivalent

The negative form

Present

1 can ride. We can play chess.

1 am. He (She) is You, They, We are able to discuss this problem at 6 o'clock today

1 am not, he (she) isn't We, you, they aren't be able to discuss this problem at 6 o'clock today

Past

1 could write the composition about my hobby.

1 was, We were able to learn this poem

1 wasn't, We were not able to learn this poem, because 1 was very tired

Future

1 shall be able sing this song.

1 won't (shan't) be able to sing this song.

Tense

Modal verb

Equivalent

The negative form

Present

1 must pay 1000 $$$

1 have to inform you about it.

1 am, he is, we are to call to police

1 don't have to inform you about it.

1 am not, he isn't, we aren't to call to police

Past

1 had to tell the truth 1 was, We were to go abroad.

1 didn't have to tell the truth

1 wasn't, We were not to go abroad.

Future

-

1 shall, They will have to read this novel

1 shan't, they (won't) have to read this novel.

Tense

Modal verb

Equivalent

The negative form

Present

May 1 come in?

1 am, he is, we are

1 am not, he isn't, we

allowed to discuss this problem with my team

aren't allowed to go abroad alone.

Past

1 might visit my friends

1 was, We were allowed to go for a walk at 9 o'clock p.m.

1 wasn't, We were not allowed to go for a walk at 10 o'clock p.m.

Future

1 shall be, They will be allowed to go to the night club with the parents.

1 shall not be, They will not be allowed to speak too much.