香港 food children school 動物 health study 港鐵 environment usa politics 運動 rank china 英國 police hongkong students government education public_health relationship park interpersonal hk_today mtr personal_development technology traditional animal 停課不停學 youth stem student energy_technology 環保 hong_kong_today 日本 conservation 美國 globalisation university space relationships science the_environment 中國 local nasa modern_china