What’s the difference?
English distinguishes auxiliaries and modal verbs. Auxiliaries (to be, to have, to do) combine with present participle or past participles or infinitive to form the verb forms of ordinary verbs. Modal verbs combine with infinitives to express ability, probability, necessity, permission, obligation, deduction etc.
| auxiliaries | modal verbs |
| am-is-are | |
| was-were | can, could, to be able to |
| has-have-had | will, won’t, shall, shan’t |
| to have to | will,would, shall, should |
When to use them
If you would like to practise the use of auxiliaries and/or modal verbs, please visit the pages modal mix and modalities.
| modal mix: (can, could, may, might, must, had to, ought, shall, should, will, would) | modalities: ability, permission, probability, deduction, necessity, request and obligation |
The form of auxiliaries
Practise the form of the auxiliaries plus known problem areas such as the short yes/no answer and the tag-questions on the pages below.