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
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