勤洗手可以预防大多数病毒感染。

Washing hands frequently can prevent most viral ___infections.

医院采取了严格的措施来防止感染的传播。

The hospital has strict measures to prevent the spread of ___infections.

她的乐观态度对全班同学产生了感染力。

Her optimism had an ___infectious impact on the whole class.