柴油机进气温度过高或空气滤清器堵塞，进气量不足导致（），使得发动机冒黑烟。
参考答案：燃烧不良
My strongest __________ is the long race and came out first in the sports meet held last week.
A．event
B．incident
C．thing
D．item
金属材料满足那些条件才能用氧-乙炔火焰切割？
