进行氧乙炔焊接时,火焰在火咀接头燃烧,原因是()
A.火咀温度过高
B.火咀没有锁紧
C.乙炔量过多
D.以上皆是
参考答案:B
Now the air in our city is ______ than it used to be. Something must be done to stop it.
A.good
B.bad
C.worse
D.better
简述液体散货装卸企业的特点