attend on

1. 照料

Jane has been attending on her sick mother for years.

简多年来一直在照料她那有病的母亲。

attend to

1. 注意; 致力于

You should attend better to your studies.

你应该更专心于学习。

2. 关心; 照料; 护理

The nurse is attending to a sick man.

护士正在照料病人。