Question 18 is based on the recording you have just heard.

18. How do positive emotions affect us?

解析：A。问题为：积极情绪是如何影响我们的？原文所在句Instead of narrowing our focus like negative emotions do, positive emotions affect our brains in ways that increase our awareness, attention and memory. They help us take in more information, hold several ideas in mind at once, and understand how different ideas relate to each other.相比消极情绪集中了我们的注意力，积极的情绪增加我们的意识、注意力和记忆，以影响我们的大脑。积极情绪帮助我们接收更多的信息，让我们在心里同时产生多想法，并且理解这些想法之间的不同之处。选项A) They expand our mind（扩大我们的心智心理），与文中信息完全一致。