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: INTERVENTIONS : Administration of flumazenil to animals after they had received a combination dose of cocaine and diazepam .
### Output Text:
INTERVENTIONS : Administration of <span class="chemical">flumazenil</span> to animals after they had received a combination dose of <span class="chemical">cocaine</span> and <span class="chemical">diazepam</span> . 