In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: METHODS : Cholinergic convulsant sensitivity was examined in alcohol - na ve Withdrawal Seizure - Prone ( WSP ) and - Resistant ( WSR ) mice .
### Output Text:
METHODS : Cholinergic convulsant sensitivity was examined in <span class="chemical">alcohol</span> - na ve Withdrawal Seizure - Prone ( WSP ) and - Resistant ( WSR ) mice . 