A visitor views the special exhibition of the "Triad of the first Viennese school: HAYDN-MOZART-BEETHOVEN" in Mozart house museum, Vienna, Austria, Feb. 19, 2020. The exhibition, part of a series of events marking the 250th anniversary of Beethoven's birth, is held from Feb. 19, 2020 to Jan. 31, 2021. (Xinhua/Guo Chen)

Exhibits are seen during the special exhibition of the "Triad of the first Viennese school: HAYDN-MOZART-BEETHOVEN" in Mozart house museum, Vienna, Austria, Feb. 19, 2020. The exhibition, part of a series of events marking the 250th anniversary of Beethoven's birth, is held from Feb. 19, 2020 to Jan. 31, 2021. (Xinhua/Guo Chen)

A visitor views the special exhibition of the "Triad of the first Viennese school: HAYDN-MOZART-BEETHOVEN" in Mozart house museum, Vienna, Austria, Feb. 19, 2020. The exhibition, part of a series of events marking the 250th anniversary of Beethoven's birth, is held from Feb. 19, 2020 to Jan. 31, 2021. (Xinhua/Guo Chen)

A visitor views the special exhibition of the "Triad of the first Viennese school: HAYDN-MOZART-BEETHOVEN" in Mozart house museum, Vienna, Austria, Feb. 19, 2020. The exhibition, part of a series of events marking the 250th anniversary of Beethoven's birth, is held from Feb. 19, 2020 to Jan. 31, 2021. (Xinhua/Guo Chen)

A visitor views the special exhibition of the "Triad of the first Viennese school: HAYDN-MOZART-BEETHOVEN" in Mozart house museum, Vienna, Austria, Feb. 19, 2020. The exhibition, part of a series of events marking the 250th anniversary of Beethoven's birth, is held from Feb. 19, 2020 to Jan. 31, 2021. (Xinhua/Guo Chen)