a can b will/shall be able to c has been able to d be able to e can
a could b was able to beat/managed to beat/succeeded in beating c could/was able to d was able to convince/managed to convince/ succeeded in convincing e could not/was not able to
a could fix/would be able to fix b could have got/would have been able to get c could have played/would have been able to play d could console/would be able to console e could unscrew/would be able to unscrew
a may/can b may not/cannot/will not be allowed to c can/may d have always been allowed to e can/may
a Could/Can/May b Could/Can; can (or May; may) c Can/Could; cannot (or May/Might; may not) d Could/Can; can (or May/Might; may) e Could/Can/May
a could not/was not allowed to b was allowed c could not/was not allowed to d could/were allowed to e could only see/were only allowed to see
a could have played/would have been allowed to play b could/would be allowed to hunt c could/would be allowed to get d could/would be allowed to go e could have joined/would have been allowed to join/could join/would be able to join
a may not b cannot c cannot d may not e cannot
a could b could/would be able to c can/will be able to d can/may e will be allowed to/may/can f were allowed g were allowed to h Could; cannot (or May/Might; may not) i cannot/should not/ought not to j cannot/ought not to/should not k will/shall be able to l would (or "should") be able to/could m can/may n be able to o could/was able to p was able to win/managed to win/succeeded in winning q was able to see/managed to see/succeeded in seeing r are not allowed s cannot t be allowed to u could/were able to v Could/May/Can w can x Can y would be able to/could; would be able to/could z can/will be allowed to/may
a Who can/could it be now?; may/could/might b may/could/might c may/might/could; may/might/could d may/might/could e may/might
a may/might/could b may/might/could c might/could/may d may/might; may/might e Do you think (that) he'll.../Is it possible/probable/likely that he'll.../Is he likely to help us...?
a can b can/may c could d cannot e cannot
a cannot b cannot c may not/might not d may not/might not e could not
a could not b might/could; might/could c could not d could not e might/could
a could/can b could/can c could/can d could/can e Could/Can
a may/might/could b may/might/could c cannot d could/can; could/can e might/could f can g could/might/may h may i may/might/could j can k Could/Can; can (or May/might; may) l can m could; could; was able to get/managed to get/succeeded in getting n Could o could/might p could q are not allowed to smoke/may not/cannot r could/would be able to s could/can t can u could v could/might/may w Do you think (that) x cannot/should not/ought not to y can z have been allowed to
a could/might b could/might c could/might d may/might/could; may/might/could; may/might/could; may/might/could e may/might/could; may/might/could
a cannot/could not b cannot/could not c cannot/could not d may not/might not; cannot/could not; may not/might not e could not/cannot
a have to b must c have to/will have to/must d have to e has to
a had to b had to c will have to/must d has had to e would have to
a need not/do not have to/do not need to b need not/do not have to/do not need to c do not have to/do not need to d need not/do not have to/do not need to e do not have to/do not need to
a may/might/could b may/might c can d could/might e Can/Could; can (or May/Might; may) f may/might/could; may/might/could; may/might/could; cannot/could not g may/might h must i cannot j must k must/will have to l need not/do not have to/do not need to m could/might n must/will (or shall) have to; cannot o had to/would have to/must; could not p may/might/could; may/might/could q cannot; must/will (or shall) have to/have to r must/have to s could t can/could u need not/do not have to/do not need to v does not have to/does not need to; does not have to/does not need to w did not have to/did not need to x cannot y cannot z were able to break/managed to break/succeeded in breaking
a need not have awaited b need not have gone c did not have to lie/ did not need to lie d need not have come e did not have to write/did not need to write
a Need/Must (or Do I have/need to) b Need/Must (or Do we have/need to) c Need/Must (or Do I have/need to) d need/must (or do you have/need to) e Need/Must (or Do I have/need to)
a must b must c must d must e must
a must not/should not/ought not to/cannot b may not c must not/cannot/should not/ought not to d must not/should not/ought not to/cannot e must not/cannot/should not/ought not to
a must b must c must d must e must
a may/might b Can/Could c must d must e must not/should not/ought not to f Could g must/will have to/have to h cannot/could not; must i should not/ought not to j should/ought to/must k need not/do not have to/do not need to/should not/ought not to/must not l cannot; must m must/will have to n can/will be able to/are able to o may/might/could; can p cannot q need not; could/might/should/ought to r did not have to/did not need to s Need/Must t must not; can/could u may not/are not allowed/permitted to; must v Do you think (that) they.../Is it possible (or probable/likely) that they.../Are they likely to play... w cannot x does not have to/does not need to y had to z was able to pass/managed to pass/succeeded in passing
a could/might b could/might c could/might d could/might e could/might
a should not/ought not to b should not/ought not to c should/ought to d should not/ought not to e should not/ought not to
a ought to/should b ought not to/should not c ought to d ought not to/should not e ought to/should
a should b should c should/would d should e shall/should
a should/ought to b should/ought to c should/ought to d should/ought to e should/ought to
a may/might/could; cannot; may/might/could b could/can c should/ought to/must d should not/ought not to/must not e cannot/could not f must/should/ought to g could not h cannot; must i may/might j must not/cannot k will have to l should not/ought not to; could not m should/ought to/could/might n could o should/ought to p could not q should not/ought not to/must not/cannot r should s cannot/must not t should not/ought not to u Should we shack/Ought we to shack v need not pay/do not have to/do not need to; can w Need/Must x ought to y must z should not/ought not to/must not/cannot
a you should arrive/you arrive b any proof (should) be/any proof is/for any proof to be destroyed c should say/says d she (should) be/for her to be here e you should like/you like; you should like/you like
a (should) train b (should) read/advised my reading c (should) clear/proposed our clearing/that we cleared d (should) study/urged his studying e the meeting (should) be postponed/was postponed/demanded to postpone the meeting
a should need/needed b (should/might) take/took c should hail/ hails d Should e could/would/should
a should/ought to/must b might/could c must d cannot e must/will have to/have to; should be/are f Need/Must (or Do I have/need to); Can't/Couldn't g must/should/ought to h need not i must j should k she (should) be/for her to be/she is; could/might l (should/might) be/was m could/might/may n must; you should learn/you learn/for you to learn o should p must q will have to r must s must t cannot; must/will have to u should not/ought not to/must not; could/might/may/can; can v you should think/you think/ridiculous to think w (should/must) x must y could not z (should); should break/broke
I have not used contractions in the answers given, but the following contracted forms are possible in colloquial language:
may not (not normally contracted)
might not (not normally contracted)
Is able to
is possible here but not so common as can
. Be able to
may replace can
(for present ability) in this key.
If we take this as a suggestion, can
should be used.
is very much preferred to was/were able to
for perception verbs. For this reason, I shall only use could
in this key.
Be allowed to
is far less usual than can
. For this reason, I shall usually use can
in this key, unless be allowed to
is the only alternative.
Although has to
is often found in American usage, I have not included it in the key.
and ought to
are also possible in this section, but the advice is less strong.
to are also possible in this section.
Verbs such as order, direct, command, urge
may be followed by the person addressed plus an infinitive with "to", but this implies that we are talking direct to him or her.