A friend asked why the Prime Minister laughed and how to answer.

1, "The Prime Minister is thinking of a humorous idea to bring joy to everyone at the evening party."

2. "The Prime Minister is thinking of an interesting joke and is ready to share it with his friends in his spare time."

3. "The Prime Minister is thinking about some interesting things and intends to write them in his diary."

4. "The Prime Minister smiled because he heard an interesting thing, which made him feel very happy and happy. He wants to share this joy with everyone so that everyone can feel his happiness. "