is called the +Present Tense+; the second, the +Past Tense+; and the third,
the +Future Tense+.

We have three other forms of the verb, expressing the action as _completed_
in the _present_, the _past_, or the _future_.

_I have walked out to-day. I had walked out when he called. I shall have
walked out by to-morrow_. The form, _have walked_, expressing the action as
_completed_ in the present, is called the +Present Perfect Tense+. The
form, _had walked_, expressing the action as _completed_ in the past, is
called the +Past Perfect Tense+. The form, _shall have walked_, expressing
an action to be _completed_ in the future, is called the +Future Perfect
Tense+.

Let the teacher give other verbs, and require the pupils to name and
explain the different tenses.

_I walk. Thou walkest. He walks. They walk_.

In the second sentence, the verb _walk_ was changed by adding _est_; and in
the third, it was changed by adding _s_. These changes are for the sake of
agreement with the person of the subject. The verb ending in _est_ agrees
with the subject _thou_ in the second person, and the verb ending in _s_
agrees with _he_ in the third person. In the fourth sentence, the subject
is in the third person; but it is plural, and so the verb drops the _s_ to
agree with they in the plural.

Verbs are said to agree in +Person+ and +Number+ with their subjects. The
person and number _forms_ will be found in Lessons 93, 94.