Ответ:

1. His work is interesting.

• Общий: Is his work interesting?
• Специальный: What is his work like?
• К подлежащему: What is interesting?
• Альтернативный: Is his work interesting or boring?
• Разделительный: His work is interesting, isn't it?

2. He spent his holidays by the sea.

• Общий: Did he spend his holidays by the sea?
• Специальный: Where did he spend his holidays?
• К подлежащему: Who spent their holidays by the sea?
• Альтернативный: Did he spend his holidays by the sea or by the lake?
• Разделительный: He spent his holidays by the sea, didn't he?