Final answer:
The sentences 'Steven likes to play baseball' and 'He lost his keys yesterday' are in active voice because the subjects are performing the actions. However, 'Bingo is played in Britain' and 'A letter was written' are in passive voice since the subjects are receiving the actions.
Step-by-step explanation:
The sentences in question can be identified as being in active or passive voice based on whether the subject is the doer or the receiver of the action. In active voice, the subject performs the action, while in passive voice, the subject receives the action.
Therefore, for the sentences given: (a) 'Steven likes to play baseball.' is in active voice because Steven is the subject performing the action (playing). (b) 'Bingo is played in Britain.' is in passive voice because the subject (Bingo) is receiving the action (being played). (c) 'He lost his keys yesterday.' is also in active voice because the subject (He) is performing the action (losing). (d) 'A letter was written.' is in passive voice because the subject (A letter) is receiving the action (being written).
Learn more about Active and Passive Voice