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: Among women with cardiovascular disease , long - term use of combined continuous HT significantly increased the risk of venous thromboembolism .
### Output Text:
Among women with cardiovascular disease , long - term use of combined continuous HT significantly increased the risk of venous thromboembolism . 