A shade for children was built last year.
Yesterday, the basement wall was painted.
Eco-friendly playgrounds are designed by her.
A new bridge will be built in this town by the company.
In each sentence, the active voice has been converted to the passive voice. The passive voice is formed by using a form of the verb "to be" (such as "is," "was," "are," "will be," etc.) along with the past participle of the main verb.
In passive constructions, the emphasis is on the action and the receiver of the action, rather than the doer of the action. The passive voice is often used when the doer of the action is not known or not important in the context, or when the receiver of the action is the focus of attention.