If you - __ studying earlier , you'd feel I more prepared for the exam. start would start had started They would have seen the fireworks if they __ here 15 minutes earlier. were would be had been If I didn't have so much work this week, I __ with you yesterday. would have gone would go had been my parents __ if my grandmother hadn't left Ireland. wouldn't meet wouldn't have met won't moot

Here are the answers with explanations:1. **If you _had started_ studying earlier, you'd feel more prepared for the exam.**This is a third conditional sentence. It describes a hypothetical situation in the past that did not happen, and its consequence. The structure is: If + past perfect (had + past participle), + conditional perfect (would have + past participle). "Had started" correctly indicates the unrealized action in the past.2. **They would have seen the fireworks if they _had been_ here 15 minutes earlier.**This is also a third conditional sentence. "Had been" shows the unrealized past condition. The sentence describes a hypothetical past situation and its consequence.3. **If I didn't have so much work this week, I _would have gone_ with you yesterday.**This is a mixed conditional sentence. It combines a present unreal condition ("If I didn't have...") with a past unreal consequence ("I would have gone..."). This structure is used when a present unreal condition affects a past result.4. **My parents _wouldn't have met_ if my grandmother hadn't left Ireland.**This is a third conditional sentence. It describes a hypothetical past situation (grandmother not leaving Ireland) and its consequence on the parents' meeting. "Wouldn't have met" correctly shows the unrealized past result.