This poor service has caused many customers to consider a competitor. Sandra refuses to bring her boyfriend over for dinner. This refusal has insulted her family. When you write a sentence in the active voice, the subject does something and the verb tells what the subject did. The passive sentence is the revese of the active.
Passive voice consists of a form of the verb to be plus a past participle.
Active voice is preferred because active verbs express meaning more vigorously than passive verbs. The students wrote their research papers. Martha rearranged her huge flower garden. Their research papers were written by the students. Her huge flower garden was rearranged by Martha.