Viruses can exist either extracellularly or intracellularly.

病毒可以存外，也可以存内。

They can exist either extracellularly where the virus is inactive and isn't capable of reproducing or intracellularly where the capsid is removed and the virus becomes active.

们可以存外，处不活跃状态，无法复制，或者内，脱掉衣壳，变得活跃。