We use the past perfect to talk about something that happened before another event in the past.

The second conditional is used to talk about hypothetical or imaginary situations that are unlikely to happen in the present or future. It’s often used to discuss dreams, wishes, or unreal scenarios.

In active voice, the subject of the sentence performs the action. In passive voice, the subject of the sentence receives the action.

The past tense of "ski" is "skied".

The past tense of "hear" is "heard".