Verbs as part of a clause

The word 'verb' is used in two rather different ways in grammar:

• to describe a word class (in a similar way to 'noun' and 'adjective')
• to describe a part of a clause

When verbs are seen as a clause element, they are on the same level as subjects, objects, complements, and adverbials. If you want to be more precise, you can describe them as verb phrases.

Tense
In modern grammar verbs have two tenses: present and past:

They want a new car. (present)
They wanted a new car. (past)

Newcomers to modern grammar find this somewhat disconcerting: 'What about I will eat' - isn't that the future tense of eat? And if it isn't the future tense, what is it?'
A more practical way of looking at things is to use the term 'tense' in a looser and wider way: to describe the form of the verb phrase that provides information about time and aspect.
In tenses, time refers to past, present, and future; aspect refers to the focus that the verb phrase gives us on what is being described.

Tense and aspect

The simplest form of the present tense is used in sentences like:

Elephants eat grass.

English has, however, more than one form of the present tense. Compare these two sentences:

I eat plenty of vegetables and I don't like chocolate.
The ladies watching the late afternoon episode of 'Crossroads' are eating Mr Kipling cakes from their local Safeway, wearing their Crimplene trouser suits.

They are both 'present' in the sense that both describe something that is true at the time of writing. But only the second describes something that is obviously happening at that moment. We call the first (eat) the simple present, and the second (are eating) the present continuous.
There is also a third form of the present. Compare this sentence with the two previous ones:

I have eaten there; it is wonderful and not ferociously expensive.

It refers to an event that happened in the past, but the speaker is still thinking about it - its effects, good or bad, are still in his or her mind. So, it is in one sense 'present'. In another sense it is past, completed - the action has been perfected. Hence the name of this tense: the present perfect.
These three versions of the present tense, simple, continuous and perfect are called aspects. They allow us to use considerable sophistication when talking about events.

©John Seely 2008