单选题 After ______ on his couch more than a dozen times, he gave up his attempt to sleep.
  • A. he overturned
  • B. his having turned over
  • C. turning over
  • D. turning up


【正确答案】 C
【答案解析】[分析] 分词作状语时，前面可以加连词when，after，before，once等。