MODALS
 

A. CAN/MAY/MIGHT

ABILITY ( = possibility)

can/could                            I can’t see you tomorrow, I’m busy.
                                           At one time I could run a mile in 4½ minutes.

able to ( = emphasis)         Yesterday I was able to finish my work by teatime.
                                           (understood: s/he did, in fact, finish it)

NB  Can you swim?            ( = Have you learned how to swim?)
       Are you able to swim? ( = Are you all right?)

may ( = perhaps)                 Don’t go into his room. He may be asleep.
                                            If you say that, he may get very angry.

        ( = permission)            May I borrow your bicycle for the afternoon?
                                            You may go now (more formal than: You can go now)

NB  (past permission)         At one time only men were allowed to vote ( = could)

might ( = less probable)      Take this torch. You might lose your way in the dark.
( = hesitation, politeness)     Might I possibly use your telephone?
( = casual request)               You might drop these letters in the post on your way by.
( = rebuke)                           You might have let me know that you were coming.

NB idiom:                           There’s only one piece left. We might as well finish it up.

B. MUST/HAVE TO

NECESSITY

must (= necessity imposed by speaker)     I must get on with my reading.
                                                                   I think you must go and have your hair cut
 
         (= deduction, supposition)          Did I say that? I must have been out of my mind.

have to ( = imposed from outside)       We have to be there at two o’clock
                                                             (we’re expected)

NB had to (= did in fact do it)              We missed the bus and had to walk.
                                                              I had to get up at five to milk the cows
                                                              (= I did do it)

NB (indirect speech)         “I must clean the car” - He said that he had to clean the car.
better:                                He said he must clean the car.
 
 

C. OUGHT TO/SHOULD

( = right/morally right)    No wonder you look pale. You ought to get more fresh air.
                                   They ought not to have told her = They should not have told her.
 

FUTURE

to be to ( = plan, order)  All right then. We are all to meet here at midnight. Agreed?
                                  The minister said that there was to be a review of teachers’ pay.

going to (= intention)      I’m going to succeed! (= I will succeed)
(action on the way)         He was going to have lunch with me, but his car broke down.
                                        I think I’m going to be sick! (I feel it coming)
                                       Look at those clouds.  It’s going to rain.
                           He drives like a madman.  He’s going to get killed one of these days.

be about to ( = soon)       Oh, hello!  I was just about to call you.

Note the differences in usage in the examples below:

a) I must see my dentist (my decision: my tooth hurts)
b) I am to see my dentist today (plan: I’ve made an appointment)
c) I have to see my dentist (I must keep the appointment, s/he’ll charge me anyway)
d) I’m going to see my dentist (I’ve made up my mind…/ I’m already on my way)
e) I’m about to see my dentist (I will see him/her in a few minutes)
 

SHALL/WILL

A. FUTURE    I shall                we shall
                        you will            you will
                        he/she/it will    they will

NB in colloquial speech 1st person shall is often replaced by will
 

B. MODAL  (includes emotional coloring)

Subject’s impulse, will or desire  =  will:  I will help you (my desire)
other than S’s impulse, will, wish = shall:  Shall I help you? ( = is it your wish?)

USAGE
determination: I will succeed next time! (my desire)
persistence: If you will eat so many cakes, you’ll get a tummy-ache. (you decide)
willingness:  He says he will agree to anything. So will I. (we are both willing)
promise: You shall have an electric train set for your birthday (I promise that you…)
request:  What shall I do next? (One part of me asks my other self)
offer:   Will you have a drink?  Or shall my wife make you a nice cup of tea?

December 2000
Erik, Moldrup