是一本教材,绝对干净,没写字。要30. ' n2 t! e8 _9 o; s( x6 m ' ^" `0 k4 j$ ?1 x P# g ; Z. [* w3 `8 W! k* pOperation of wastewater treatment Plant, ( {& S) e, _3 I% O T* m s- @0 | V) s0 f& F
A field study training program, : ]# V: \5 F+ z; j' u2 X; u' t: J# Q1 z: C7 P
Volume 1 , Seventh Edition