工业废物是指工业生产过程中，排入环境的各种废渣、污泥、（）等。
A.粉尘
B.垃圾
C.杂质
D.废气
参考答案：A
The factory has developed a lot____ we visited the advanced worker five yeas ago.
A．when
B．which
C．that
D．where
鸣天鼓
