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 clear reduction of BS synthesis was found in bile - diverted rats treated with EE , yet biliary BS composition was only minimally affected .
### Output Text:
A clear reduction of <span class="chemical">BS</span> synthesis was found in bile - diverted rats treated with <span class="chemical">EE</span> , yet biliary <span class="chemical">BS</span> composition was only minimally affected . 