A painter hangs his or her finished pictures on a wall, and everyone can see it. A composer writes a work, but no one can hear it until it is performed. Professional singers and players have great responsibilities, for the composer is utterly dependent on them.

 A student of music needs as long and arduous a training to become a performer as a medical student needs to become a doctor. Most training is concerned with technique, for musicians have to have the muscular proficiency of an athlete or a ballet dancer. Singers practice breathing every day, as their vocal chords would be inadequate without controlled muscular support. String players practice moving the fingers of the left hand up and down, while drawing the bow to and fro with the right arm----????????two entirely different movements. Singers and instruments have to be able to get every note perfectly in tune. Pianists are spared this particular anxiety, for the notes are already there, waiting for them, and it is the piano tuner's responsibility to tune the instrument for them. But they have their own difficulties; the hammers that hit the string have to be coaxed not to sound like percussion, and each overlapping tone has to sound clear. This problem of getting clear texture is one that confronts（使面对）student conductors: they have to learn to know every note of the music and how it should sound, and they have to aim at controlling these sounds with fanatical but selfless authority. Technique is of no use unless it is combined with musical knowledge and understanding. Great artists are those who are so thoroughly at home in the language of music that they can enjoy performing works written in any century.

19. In writing this passage, the purpose of the author is ___________.

   A. to tell us we use different sense at paints and music

   B. to recommend music needs more technique

   C. to inform us that to become a musician needs long and arduous training

   D. for the students who are to go in for music

20. If you are a string performer, you have to _____________.

   A. use your left hand to draw the bow and the right to move up and down

   B. have your both hands perform the same movements.

   C. own technique, musical knowledge and understanding

   D. practice more and more without any training

21. The problem of getting clear texture is that ____________.

  A. confronts student conductors

  B. the student conductors have to know every note and how it should sound and how to control the sounds fanatically.

 C. the sounds are too easy to control

 D. the composer’s work cannot be seen on the wall.

22. According to the passage, _______________.

 A. a composer cannot perform the music at all.

 B a composer has to utterly depend on student conductors

 C. student conductors need more training and knowledge on music to be great artists.

 D. Great artists are thoroughly at home in the language of music.