SINGLE WORD VERBS AND VERB STRINGS
A verb may be just one word:
The moon's cycle, not the sun's, GOVERNS
the tides. Therefore, low tide COMES
at a later time each day.
Often, however, a verb is a string of words made of a main verb with one or more auxiliaries in front of it.
The tide WAS CHANGING at 10:30 yesterday morning. It SHOULD BE TURNING today at about 11:10 A.M. We probably COULD HAVE WAITED
until noon for our fishing trip.
The main verb identifies the event which the sentence is reporting. The auxiliaries tell more about the time or conditions of the event, and they always come before the main verb. The verb string is the combination of auxiliaries and main verb acting together to play the role of verb in a sentence. In the following exercises, the verbs will be analyzed and marked like this:
single-word verb = SV
main verb = MV
auxiliary = X
Verbs in the simple present or simple past tense consist of just one word.

Verbs that emphasize the continuation of an event include some form of to be as an auxiliary (am, is, are, was, were, being).

Verbs that emphasize the completion of an event include some form of to have as an auxiliary (have, has, had).

Verbs that express a future event include the auxiliary will or shall.

Verbs may include several other auxiliaries to express shadings of time or condition. These additional auxiliaries are: do, does, did, can, could, should, would, may, might, must.

Application 3
The following words may be used as auxiliaries within verb strings:

The words in the blue-shaded area of the above chart may sometimes act as single-word verbs:
I AM your brother. You HAVE the same kind of eyes as I DO.
The rest of the auxiliaries in the chart work only in verb strings:
Everyone WILL BE happy. They MUST HAVE BEEN EXPECTING something.
Learn the auxiliaries in the chart. They will help you to find verb strings.
Application 4
Many auxiliaries can shrink into shorter forms called contractions.
I'M LOOKING forward to this evening with Arny's boss. After supper we'LL WATCH the game unless she'D PREFER to play cards.
Here are some common contractions. Click HERE for a printable one-page duplicate of this chart.