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: A dose of 0 . 5 mg . / kg . produced a reduction of almost 50 % of the behavioral score induced by CP 200 mg . / kg .
### Output Text:
A dose of 0 . 5 mg . / kg . produced a reduction of almost 50 % of the behavioral score induced by <span class="chemical">CP</span> 200 mg . / kg . 