contagious

他们的笑容感染了周围的人。

Their smiles are ___contagious.

麻疹是一种高度传染性的疾病，通过空气传播。

Measles is a highly ___contagious disease that spreads through the air.

这种病毒非常容易传染，所以请保持社交距离。

This virus is highly ___contagious, so please maintain social distance.