Individual steps in a use case should be written in the form
select one:
a. direct object, verb, subject, preposition, indirect object
b. direct object, subject, verb, preposition, indirect object
c. subject, verb, preposition, indirect object, direct object
d. subject, verb, indirect object, preposition, direct object
e. subject, verb, direct object, preposition, indirect object

Individual steps in a case should be written in the form e. Subject, Verb, Direct Object, Preposition, Indirect Object.

Explanation:

A use case implies the description of an action or activity. In other words, it involves a description of the actions that a a person will have to do in order to carry out a process. The syntactic structure of the instructions should always be in the direct form, so as to be clear and avoid any mistakes in the process. For example:

"In case of emergency, (you) [Implicit Subject] use [Verb] the hammer [Direct Object] to break the glass [Indirect Object]"