_______ April 20th , 2013, a terrible earthquake happened in Ya’an city, Sichuan
A:In
B:On
C:At
①关键部分的功能对整体的功能具有决定性作用
②人为事物的联系形成之后便独立于意识之外
③部分的功能及其变化会影响整体的功能
④把握联系的多样性才能正确认识和掌控事物
—I guess Tom did it, for he was on duty today.