Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the  correct  answer  to each of  the questions  from  36  to  42.

          Vietnam officially became a full member of the Association of Southeast Asian Nations (ASEAN) on July 28, 1995. Since then, Vietnam has worked together with other ASEAN member countries to reinforce regional cooperation and made great contributions to maintaining peace, stability and reconciliation in the region. 

          In the past years in the ASEAN, Vietnam has reaped (obtained) many successes in all social and economic fields. The country has gradually restructured its administrative apparatus to suit a market economy and to integrate into the international community. Vietnam has made a good impression on ASEAN countries with its achievements in economic development especially in hunger eradication and poverty alleviation. ASEAN countries' investment into Vietnam has also increased sharply. With a high economic growth rate averaging seven percent each year, Vietnam has been able to decrease economic gap slightly with Thailand, Singapore, Malaysia, Indonesia, the Philippines and Brunei. 

          In addition, Vietnam actively works to integrate culturally and socially with the Southeast Asian region while preserving its own cultural features. Thirteen is not a long period for such an important political event but what has been achieved in relations between Vietnam and the association is creating splendid prospect for the future.

How long has Vietnam been a full member of ASEAN?