Two people talking near a green blackboard. E=mc² formula written on a blackboard. One person is standing and listening. The other person is pointing to the blackboard. Silhouttes of the people are also available separately.
黑板附近的人
blackboard、cartoon、colour、discussion、education、formula、inkscape、people、school、science、students、talk、two
黑板、動畫片、顏色、討論、教育、式、Inkscape中、人、學校、科學、學生們、談論、二
資料來源：openclipart ( https://openclipart.org/ )