Category 1: be, have, do
These forms of to be, to have, and to do are used before the main verb.
Their purpose is to change time or emphasis.
Unlike other structure words, these auxiliary verbs |
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Category 2: Modal auxiliaries
The list below shows all of the modal auxiliaries:
Present |
can |
may |
will |
shall |
must |
Past |
could |
might |
would |
should |
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Unlike the auxiliaries be, have, and do, modal auxiliaries |
1. do not use inflectional endings (-s, -ed, -ing, -en) |
2. cannot function as main verbs. |
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When a verb phrase uses both kinds of auxiliary verbs, the modal auxiliary always precedes the be, have, or do auxiliary.
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