What's the little white flower on the school wall?

The little white flowers on the school wall are white lilacs. According to relevant data, there are three kinds of green plants in primary and secondary schools in China: morning glory, Parthenocissus tricuspidata and white lilac. White lilacs are white, with oval sepals, slightly longer than calyx tubes, and fragrant, so the small white flowers on the school wall are white lilacs.