单选题 4, Heat exhaustion is a condition caused by ______ to sunlight or another heat source which often results in dehydration and salt depletion.
  • A. a reaction to
  • B. overexposure
  • C. an limitation of
  • D. an absence of
【正确答案】 B
【答案解析】[解析] 本题空格处是说由过度暴露在阳光下引起的。B项的overexposure“过度暴露”符合题意。其他三项a reaction to“反应”；an limitation of“局限”；an absence of“缺乏”都不正确。