Modal verbs
General principles
The auxiliary modals "would", "may", "might", "should", " must", "ought to", "can", "could", "will", " shall" are invariable. They exist only in the present, and unlike most verbs in the simple present, their form does not change in the third person singular.
Modal verbs are auxiliaries, or "helping" verbs: they are used in conjunction with another verb (in infinitive form) as a way to modify its meaning. Modals can nuance the meaning of the principal verb in a number of ways:
– Possibility or ability, by "can" or "could"- I can do this job.
- Could you please do the dishes?
–Possibility or permission by "may" or "might" often translated in other languages by a different mood, such as the subjunctive).
- I may finish my paper tonight.
- You may come with us, if you wish.
- It might be helpful to have a map.
– Obligation, or moral obligation, by "must", "ought to" o "should":
- Students must hand in their work on time.
- You ought to see a doctor.
- You should never play with fire.
Note that "must" can also indicate probability:
- You must be exhausted!
- He must play tennis pretty well.
The modal verb "would" is used to express the conditional:
- If he had time, he would pick up some groceries.
The modal verb "will" expresses future:
- The train will arrive in an hour.
Contractions
After a pronoun subject, "would" is often contracted into "–'d" ("I'd", " we'd", "she'd", etc.) while "will" is contracted into "–'ll" (" I'll", "you'll", "they'll", etc.). After all modal verbs, the word " not" of the negative can be contracted into "–n't" ("wouldn't", " shouldn't", etc.).
Exceptions: "will not" becomes "won't". "Can not" can also be written "cannot"; in its contracted form, the "n" is not doubled: "can't".
Note: The contraction of the modal verbs "shall," "ought," and "may," is considered slightly archaic or literary.
examples of contractions:
- I wouldn't (would not) do that, if I were you!
- They'll (they will) never believe it!
- She won't (will not) bother you anymore.
Question tag phrases ("isn't it," "wasn't it," etc.)
Modals can be used in a negative interrogative form after an affirmative expression. The function of such an expression is to prompt the listener to reassert or reaffirm what has been stated:
- You would like to go with us, wouldn't you?
- You can understand that, can't you?
The modal verb used in the interrogative tag is generally the same as the modal found in the main clause; the subject pronoun is also repeated.
After a negative sentence, the modal tag phrase is in the affirmative:
- You wouldn't want to try it, would you?
- She won't be back, will she?