1. As conditions deteriorate, city populations would eventually collapse due to malnutrition, disease, and perhaps violence.
    由于条件的恶化，城市人口最终会因营养不良、疾病蔓延，也许还因暴力行为而锐减。

2. It was pathetic to watch her condition deteriorate day by day.
    看着她的健康状况日益恶化真是可怜。

3. It was pathetic to watch her condition deteriorate day by day.
    看着她的健康状况日益恶化真是可怜。