单选题 The pressure ______ causes Americans to be energetic, but it also puts them under a constant emotional strain.
  • A. to compete
  • B. competing
  • C. to be competed
  • D. having competed
【正确答案】 A
【答案解析】[解析] 动词不定式作定语时，不定式置于被修饰的名词之后。A项与C项的差别在于语态，compete属不及物动词，不能构成被动形式。