单选题 They found the lecture hard ______.
  • A. to understand
  • B. to be understood
  • C. to have been understood
  • D. to have understood


【正确答案】 A
【答案解析】[分析] 动词不定式在difficult，easy，fine，hard，impossible，nice等形容词后出现的不定式只能用主动式。本题正确答案为A。