In any English sentence there are either zero, one, two or three actants.

Actants are the “participants” of the sentence. They are either people or things. In (1) below the action of “to rain” itself is the “zero” actant.

(1) It is raining.

“It” is the dummy subject.

In (2) and (3) the subjects “Peter” and “Charlene” are the actants respectively.

(2) Peter is swimming.
(3) Charlene is a teacher.

In (2) the act itself is performed by the subject “he”. In (3) “Charlene” and “the teacher” are one and the same person. Only one actant is involved in the description of the situation. In (4) and (5) below there are two actants. In (4) they are “Dave” and “the ball”. In (5) they are “the people” and “Hilary”. Since “Hilary” and “he president” are one and the same person we do not count the president as an actant.

(4) Dave kicked the ball.
(5) The people made Hilary the president.

In (6) we have three actants.

(6) Tony gave Leslie a presnet.

They are “Tony”, “Leslie” and “a present”.

Technically, it is possible to have more actants (and more than likely some languages do) but in English our limit seems to be three. More complex sentences will be simple sentences in disguise.