We enjoyed the picnic until a thunderstorm intervened.

那次们玩得很痛快, 后来一场使它中断了。

THUNDERSTORMS are notoriously unpredictable, as many a drenched picnicker can attest.

雷难以预测，对此那些被淋得透湿者深有体会。

Thunderstorm is common in summer.

雷电交加在夏天很常见。

Clouds gather before a thunderstorm.

在来临之前云层聚集。