Emulsion oils and sodium nitrite are both approved additives， but the latter cannot be used if any pipes are （） or if any soldered joints exit.

The mice with cherry red skin were ( ) A: Hypoxic rats B: carbon monoxide poisoning C: sodium nitrite poisoning D: Potassium cyanide poisoning mice E: normal mice

4. Which of the following conditions can cause enterogenous cyanosis? A: Carbon monoxide poisoning B: Nitrite poisoning C: Cyanide poisoning D: Oxygen poisoning E: Intestinal endotoxin poisoning