所有乐器前都要加the吗?请列举几种情况说明,

对，但是所有的球类运动都不加the
如play the piano,play the drum, play the violin

是的，钢琴 play the piano
小提琴 the violin
乐器前要加the

对,like :play the violin,play the guitar
但运动前不加定冠词the,like:play football,play basketball,