| I ____ have been more than six years old when the accident happened. A. shouldn’t B. couldn’t C. mustn’t D. needn’t |
| I ____ have been more than six years old when the accident happened. A. shouldn’t B. couldn’t C. mustn’t D. needn’t |
| B |
| 从句意和时间状语从句的时态判断。本句是对过去否定情况的推测。故选B。 |