Economic Community of West African States (ECOWAS) (a regional group initially of sixteen countries, founded on May 28, 1975 when sixteen West African countries signed the Treaty of Lagos) (http://www.ecowas.int/)是什么意思 Economic Community of West African States (ECOWAS) (a regional group initially of sixteen countries, founded on May 28, 1975 when sixteen West African countries signed the Treaty of Lagos) (http://www.ecowas.int/)怎么读