Which sentence contains a verb in passive voice?
a. where did you find my coat?
b. a commencement speech has already been written by the principal.
c. times like these are precious.
d. our neighbors invited us over for a barbecue.

Sentences can either used as active or passive voices. A sentence is active the subject pf the sentence is the one performing the action with the formula: subject + verb + receiver of the action. A sentence is passive when the subject is the one upon by the verb. The formula is subject + be + verb past participle + receiver of the action. In the sentences above, the answer is letter B: A commencement speech has already been written by the principal.