worrywart /ˈwʌrɪˌwɔːt/

• 1. 

  N-COUNT If you refer to someone as a worrywart, you mean that they worry too much or worry about things that they should not worry about. 杞人忧天的人 [非正式]

  例：

  Some worrywarts have predicted that if the scientists actually do create a new universe, it might destroy the existing one.

  一些杞人忧天的人预测说，假如科学家真的能够造出一个新宇宙，它也许会摧毁现存的宇宙。