It remains a puzzle about why our outermost planet exists.
A: problem
B: mystery
C: question
D: point
A: problem
B: mystery
C: question
D: point
举一反三
- shewas（puzzle）（） A: girl B: woman C: problem D: mystery
- These computer programs are a ______ to me. A: problem B: difficulty C: puzzle D: question
- game/ mystery /see/ why/ flock /so/ this /many /remains/ to/ the /people
- Pluto, the outermost planet of the solar system, ( ) photographically in March 1930. Pluto, the outermost planet of the solar system, ( ) photographically in March 1930.
- 18. She had a good job but she suffered a setback with her health. A: problem B: question C: puzzle D: tiredness