单选题 The relation of the earth on its axis is responsible for the ______ of periods of light and darkness.
  • A. alteration
  • B. alternation
  • C. alternative
  • D. altercation
【正确答案】 B
【答案解析】[解析] 各项的意思是：alteration“变更，改造，变动”；alternation“交替运转，轮流，间隔”；alternative“二中择一，可供选择的事物”；altercation“争吵，口角”。