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: The children received gastrointestinal decontamination and high doses of intravenous benzodiazepines in an attempt to control the choreoathetoid movements .
### Output Text:
The children received gastrointestinal decontamination and high doses of intravenous <span class="chemical">benzodiazepines</span> in an attempt to control the choreoathetoid movements . 