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: i . v . RESULTS : CP dose - relatedly induced marked behavioral modifications in male rats : breathing rate decrease , closing of the eyes and occurrence of specific postures .
### Output Text:
i . v . RESULTS : <span class="chemical">CP</span> dose - relatedly induced marked behavioral modifications in male rats : breathing rate decrease , closing of the eyes and occurrence of specific postures . 