Introducing an exhibition featuring work by participants of the 13th mid-level metropolitan administrator training session at City Hall yesterday, the governor said the number of elderly was rising, while the number of children gradually declined because of people’s desire to have smaller families.As a result, the city has to call on young people to be more socially responsible, he said. The city will push for all parties to see the importance of senior citizens and create a society where people of all ages could co-exist happily and in harmony, he added.