S + can / could / must / have to / may / might / will / would / shall / should / ought to + V ( thể nguyên mẫu )..................
Thể khẳng định: S + (can/could/must/have to/may/might/will/would/shall/should/ought to) + V (bare-infinitive)
Thể phủ định: S + (can/could/must/have to/may/might/will/would/shall/should/ought to) + not + V (bare-infinitive).
Thể nghi vấn: (Can/Could/Must/Have to/May/Might/Will/Would/Shall/Should/Ought to) + S + V (bare-infinitive).