單項選擇題
(1)黑煙或灰煙(2)藍煙(3)黃煙(4)白煙
A.(1)(2)(3)
B. (1)(2)(4)
C. (2)(3)(4)
D. (1)(2)(3)(4)
(1)黑煙或灰煙(2)藍煙(3)黃煙(4)白煙
A.(1)(2)(3)
B. (1)(2)(4)
C. (2)(3)(4)
D. (1)(2)(3)(4)