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: CONCLUSIONS : The combination of carboplatin and liposomal doxorubicin has modest activity in patients with recurrent cervical carcinoma .
### Output Text:
CONCLUSIONS : The combination of <span class="chemical">carboplatin</span> and liposomal <span class="chemical">doxorubicin</span> has modest activity in patients with recurrent cervical carcinoma . 