1 . World Environment Day is a UN Environment-led global event,     1     takes place on June 5 every year and is celebrated by thousands of communities worldwide. Since it began in 1972, it has grown to become the     2     (large) of all the celebrations of environment each year. China owns half the world’s electric vehicles and 99% of the world’s electric buses. By     3     (host) World Environment Day 2019, the Chinese government will be able to showcase its innovation and progress toward a cleaner environment.