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: Patients were treated with oral FDC of T + A or A QD before breakfast for 12 weeks ; blood pressure ( BP ) and heart rate were measured in the sitting position .
### Output Text:
Patients were treated with oral FDC of T + A or A QD before breakfast for 12 weeks ; blood pressure ( BP ) and heart rate were measured in the sitting position . 