optimism

他富有感染力的乐观主义帮助团队克服了无数挫折。

His infectious ___optimism helped the team overcome numerous setbacks.

我们心中充满了乐观、好奇以及荒唐的恐惧交织在一起的复杂情感。

Our hearts were full with a mixture of ___optimism, curiosity and absurd fears.

当他谈论公司未来时，声音中带着一丝乐观。

There was a note of ___optimism in his voice as he spoke about the company's future.