1. 如果：on business 因公 | on condition that 如果 | on duty 上班,值班

2. 如果...;在...条件下：on business 因事,因公 | on condition that 如果...;在...条件下 | on credit 赊(购)

3. 在...条件下：on business / / 因公,因事 | on condition that / / 在...条件下 | on duty / / 值班,上班

4. 条件是：condition n. 条件,情形,环境 | on condition that/条件是 | be in good condition/完好无误;