[单项选择]　　　 Composers today use a wider variety of sounds than ever before, including many 　　　 that were once considered undesirable noises. Composer Edgard Varese (1883-1965) 　　　 called thus the "liberation of sound...the right to make music with any and all sounds." 　　　 Electronic music, for example―made with the aid of computers, synthesizers, and (5) electronic instruments―may include sounds that in the past would not have been 　　　 consdered musical Environmental sounds, such as thunder, and electronically generated 　　　 hisses and blips can be recorded, manipulated, and then incorporated into a musical 　　　 composition. But composers also draw novel sounds from voices and nonelectronic 　　　 instruments. Singers may be asked to scream, laugh, groan, sneeze, or to sing phonetic (10) sounds rather than words. Wind and string players may lap or scrape their instruments. 　　　 A brass or woodwind player may hum while playing, to produce two pitches at once; a 　　　 pianist may re
A. chart the history of innovation in musical notation
B. explain the logic of standard musical notation
C. design and develop electronic instruments
D. indicate how particular sounds should be produced

[单项选择]　　　 Composers today use a wider variety of sounds than ever before, including many 　　　 that were once considered undesirable noises. Composer Edgard Varese (1883-1965) 　　　 called thus the "liberation of sound...the right to make music with any and all sounds." 　　　 Electronic music, for example―made with the aid of computers, synthesizers, and (5) electronic instruments―may include sounds that in the past would not have been 　　　 consdered musical Environmental sounds, such as thunder, and electronically generated 　　　 hisses and blips can be recorded, manipulated, and then incorporated into a musical 　　　 composition. But composers also draw novel sounds from voices and nonelectronic 　　　 instruments. Singers may be asked to scream, laugh, groan, sneeze, or to sing phonetic (10) sounds rather than words. Wind and string players may lap or scrape their instruments. 　　　 A brass or woodwind player may hum while playing, to produce two pitches at once; a 　　　 pianist may re
A. The use of nontraditional sounds in contemporary music
B. How sounds are produced electronically
C. How standard musical notation has beer, adapted for nontraditional sounds
D. Several composers who have experimented with the electronic production of sound

[单项选择]Many people consider the wider use of biofuels a promising way of reducing the amount of surplus carbon dioxide (CO₂) being pumped into the air by the world’s mechanized transport. The theory is that plants such as sugar cane, maize (corn, to Americans), oilseed rape and wheat take up CO₂ during their growth, so burning fuels made from them should have no net effect on the amount of that gas in the atmosphere.
Theory, though, does not always translate into practice, and just as governments have committed themselves to the greater use of biofuels, questions are being raised about how green this form of energy really is. The latest comes from the International Council for Science (ICSU) based in Paris.
The ICSU report concludes that, so far, the production of biofuels has aggravated rather than ameliorated global warming. In particular, it supports some controversial findings published in 2007 by Paul Crutzen of the Max Planck Institute for Chemistry in Ge
A. The ICSU researchers.
B. Previous researchers.
C. The IPCC researchers.
D. Global governments.