Student or Learner
could you please confirm that the following sentences are correct?
1.we mustn't shout in the classroom.
(past tense) we weren't allowed to shout in the classroom.
2.That will be John on the phone.
(past tense) That will have been John on the phone.
3.You should be more careful.
(past tense) ?
It looks like you are learning modals. If so, bear in mind that the modals have similarities of meanings. The problem is figuring out the boundaries that distinguishes them. I doubt that it is useful to learn modals as past/present tenses, I try to avoid making that distinction. But some do say that it works like this: can/could, may/might, will/would, shall/should... but when it comes to must... there is no corresponding "past tense".