harbinger|harbingers

这位科学家被誉为气候危机的先行者。

This scientist is regarded as the ___harbinger of climate crisis.

乌云通常是暴风雨的先兆。

Dark clouds are often ___harbingers of a storm.

早春的第一朵花是温暖天气的先兆。

The first flower in early spring is a ___harbinger of warm weather to come.