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: CASE : A 33 - year - old woman with a 5 - week gestation had recently received CC for ovulation induction and presented with chest pain .
### Output Text:
CASE : A 33 - year - old woman with a 5 - week gestation had recently received <span class="chemical">CC</span> for ovulation induction and presented with chest pain . 