1. Article 7. Issuance, form and irrevocability of undertaking.

2. The irrevocability of death is further questioned by the appearance at Clarissa's party of her old nurse and her aunt Helen, previously described as deceased.

3. He mainly explains his philosophy of time about"the present"through three concepts:irrevocability, events and reconstruction.

4. The authorship Right is an important personal right to author and is protected by law, with characteristic of non negotiability, perpetuity and irrevocability.

5. In addition, the commodity market has three apparent characteristics: investment irrevocability, indetermination of policy and economy as well as the interactivity of main body.