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 objective of this study was to assess minor neurological dysfunction , cognitive development , and somatic development after dexamethasone therapy in very - low - birthweight infants .
### Output Text:
The objective of this study was to assess minor neurological dysfunction , cognitive development , and somatic development after <span class="chemical">dexamethasone</span> therapy in very - low - birthweight infants . 