单选题 Heavy ______ to environmental tobacco smoke at work has been shown to double the risk of lung cancer.
  • A. touch
  • B. contact
  • C. exposure
  • D. encounter
【正确答案】 C
【答案解析】touch：接触，联系(with)，触摸；contact：接触(with)；exposure：接触(to)，暴露于；encounter：遇到，遭遇。