56. D) They are major contributors to environmental problems.
57. C) The desire to generate profits.
58. C) They believe building such a system is too costly.
59. A) It helps businesses to save and gain at the same time.
60. B) They do much better than their counterparts in terms of revenues.

精品四六級考試課程：英語四級【簽約班】??英語六級【簽約班】??英語零基礎直達CET4級考試版