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: RESULTS : The maximum nonsedating doses were : morphine , 3 . 2 mg / kg ; CNSB002 10 . 0 mg / kg ; 5 . 0 mg / kg CNSB002 with morphine 3 . 2 mg / kg in combination .
### Output Text:
RESULTS : The maximum nonsedating doses were : <span class="chemical">morphine</span> , 3 . 2 mg / kg ; <span class="chemical">CNSB002</span> 10 . 0 mg / kg ; 5 . 0 mg / kg <span class="chemical">CNSB002</span> with <span class="chemical">morphine</span> 3 . 2 mg / kg in combination . 