— Someone is knocking at the door. Who _____ it be?
| — Someone is knocking at the door. Who _____ it be? — It must be the milkman. |
| [ ] |
| A. may B. must C. can  D. need |
可能相似的问题
你能帮帮他们吗
| — Someone is knocking at the door. Who _____ it be? — It must be the milkman. |
| [ ] |
| A. may B. must C. can D. need |
你能帮帮他们吗