我们的讨论涵盖了各种话题，例如气候变化和核武器。

Our discussion ranged over various ___topics, such as climate change and nuclear weapons.

食物是我最喜欢的话题之一。

Food is one of my favourite ___topics of conversation.

会议的主要议题是未来计划。

The main ___topic of the meeting was future plans.