她那持续的快乐极富感染力，提振了整个团队的士气。

Her constant ___cheerfulness was contagious, lifting the spirits of the entire team.

在许多文化中，黄色在象征意义上与欢快和乐观联系在一起。

In many cultures, the colour yellow is symbolically linked to ___cheerfulness and optimism.

尽管天气阴沉，但由于生机勃勃的花朵，一种愉悦感弥漫在整个春日的花园里。

Despite the overcast weather, a sense of ___cheerfulness pervaded the spring garden, thanks to the vibrant blooms.