A.無毒 B.同樣有毒 C.有劇毒 D.危險就解除了
A.比空氣略重 B.比空氣略輕 C.與空氣一樣重 D.不好判斷
A.0.13ppm B.4.6ppm C.10ppm—15ppm D.0.13ppm—4.6ppm