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: There were dose - dependent increases in FEV1 and FEF25 - 75 ( p less than 0 . 001 ) , and pretreatment with HDS did not displace the DRC to the right .
### Output Text:
There were dose - dependent increases in FEV1 and FEF25 - 75 ( p less than 0 . 001 ) , and pretreatment with HDS did not displace the DRC to the right . 