单选题 The last guests to reach the hotel ______ at 12 o'clock at night.
  • A. checked out
  • B. checked up
  • C. checked in
  • D. check on
【正确答案】 C
【答案解析】[解析] 各项的意思为：checked out付帐离开，检查；checked up调查，核对；checked in登记，报到；check on检查。所以，本题选C。