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: Aspirin does not seem to affect CVD mortality or all - cause mortality in either men or women .
### Output Text:
<span class="chemical">Aspirin</span> does not seem to affect CVD mortality or all - cause mortality in either men or women . 