Basic Clause Patternsfollowed by a verb in its past participle form.
The passive be must be mentioned here, too. Unlike the progressive be, it
is followed by a past participle:
(48) Bill was followed by the FBI.A clause may contain several auxiliary verbs:
(49) Bill may have been being followed by the FBI.But they will always occur in the order:
(50) (Modal) (Perfective have) (Progressive be) (Passive be)Each auxiliary is enclosed in parentheses because each is optional. and
each clause may contain from zero to four auxiliary verbs.
Although the order of auxiliary verbs is invariant, the position of the first
auxiliary verb with respect to the subject of its clause depends upon the type
of clause involved. In indicative clauses, it occurs between the subject and
the verb phrase. In interrogatives, the first auxiliary is placed to the left of
the subject. In negative clauses, the negator, not, is placed immediately after
the first auxiliary verb. Compare the indicative (a), interrogative (b), and
negative (c) clauses below:
(51) a. Bill must leave.
b. Must Bill leave?
c. Bill must not leave.
(52) a. Bill is leaving.
b. Is Bill leaving?
c. Bill is not leaving.
(53) a. Bill has left.
b. Has Bill left?
c. Bill has not left.
(54) a. The postcard was mailed yesterday.
b. Was the postcard mailed yesterday?
c. The postcard was not mailed yesterday.
(55) a. Bill should have been being followed by the FBI.
b. Should Bill have been being followed by the FBI?
c. Bill should not have been being followed by the FBI.