單項(xiàng)選擇題
A.10PPM B.15PPM C.20PPM D.30PPM
A.10% B.20% C.30%
A.1 B.2 C.3
A.不一定 B.必須 C.視情況而定 D.不必
A.3 B.5 C.7 D.8
A.20PPM~100PPM B.100PPM~300PPM C.300PPM以內(nèi) D.10PPM~20PPM
A.10PPM以內(nèi) B.10PPM~20PPM C.20PPM~100PPM D.100PPM~300PPM
A.300PPM以內(nèi) B.10PPM~20PPM C.20PPM~100PPM D.100PPM~300PPM
A.20PPM~100PPM B.10PPM~20PPM C.300PPM以內(nèi) D.100PPM~300PPM