Verb forms with modals
The modal verbs are can, could, may, might, must, shall, should, will, and would. (Ought to is also considered a modal verb.) The modals are used with the base form of a verb to show ability, certainty, necessity, permission, obligation, or possibility.
Modals and the verbs that follow them do not change form to indicate tense. For a summary of modals and their meanings, see the chart below.
The modal will must be followed by the base form launch, not the present tense launches.
The modal could must be followed by the base form speak, not the past tense spoke.
TIP: Do not use to before a main verb that follows a modal.
Modals and their meanings
Can
| general ability (present) | Ants can survive anywhere, even in space. Jorge can run a marathon faster than his brother. |
| informal requests or permission | Can you tell me where the light is? Sandy can borrow my calculator. |
could
| general ability (past) | Lea could read when she was only three years old. |
| polite, informal requests or permission | Could you give me that pen? |
may
| formal requests or permission | May I see the report? Students may park only in the yellow zone. |
| possibility | I may try to finish my homework tonight, or I may wake up early and finish it tomorrow. |
might
| possibility | Funding for the language lab might double by 2018. |
NOTE: Might usually expresses a stronger possibility than may.
must
| necessity (present or future) | To be effective, welfare- |
| strong probability | Amy must be nervous. [She is probably nervous.] |
| near certainty (present or past) | I must have left my wallet at home. [I almost certainly left my wallet at home.] |
should
| suggestions or advice | Diabetics should drink plenty of water every day. |
| obligations or duties | The government should protect citizens’ rights. |
| expectations | The books should arrive soon. [We expect the books to arrive soon.] |
will
| certainty | If you don’t leave now, you will be late for your rehearsal. |
| requests | Will you help me study for my psychology exam? |
| promises and offers | Jonah will arrange the carpool. |
would
| polite requests | Would you help me carry these books? I would like some coffee. [Would like is more polite than want.] |
| habitual or repeated actions (in the past) | Whenever Elena needed help with sewing, she would call her aunt. |