单选题 Many parents encounter occasions when their child doesn't {{U}}turn in{{/U}} their homework assignments.
  • A. participate in
  • B. hand in
  • C. engage in
  • D. invest in
【正确答案】 B
【答案解析】[解析] turn in：上交，交，自首；participate in：参加，参与；hand in：交(作业)；engage in：从事；invest in：投资，投入