—————————— is not clear.
A: what caused the accident
B: what did cause the accident
A: what caused the accident
B: what did cause the accident
举一反三
- What caused the accident ______ on the road.
- Officials have not yet __________ what caused the accident or the explosion.
- Unfortunately, those who_____ the accident cannot recall what happened, Therefore the cause of the accident remains a mystery.
- ― _____ An accident has happened. A. Where was the accident? B. What happened? C. When was the accident? D. Why did it happen?
- ()caused the accident is still a complete mystery A: What B: That C: How D: Where