资料题：According to the passage, the keys to（　）。social development and material progress are

It has been thought that Africans are born with musical talent.Because music is so important in the lives of many Africans and because so much music is performed in Africa, we are inclined to think that all Africans are musicians.The impression is strengthened when we look at ourselves and fund that we have become largely a society of musical spectators.Music is important to us, but most of us can be considered consumers rather than producers of music.We have records, television, concerts, and radios to fu161 many of our musical needs.In most situations where music is performed in our culture, it is not difficult to distinguish the audience from the performers, but such is often not the case in Africa.Alban Ayipaga, a semiprofessional musician from northern Ghana, says that when his flute and drum ensemble is performing,"Anybody can take part" .This is true, but some musicians recognize that not all people are equally capable of takingpart in the music.Some can sing along with the drummers, but relatively few can drum and even fewer can play the flute along with the ensemble.It is fairly common in Africa for there to be an ensemble of expert musicians surrounded by others who join in by clapping, singing, or somehowadding to the totality of musical sound.Performances often take place in an open area (that is, not on a stage) and so the lines between the performing nucleus and the additional performers, active spectators, and passive spectators may be difficult to draw from our point of view.