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: A metoprolol - terbinafine combination induced bradycardia .
### Output Text:
A <span class="chemical">metoprolol</span> - <span class="chemical">terbinafine</span> combination induced bradycardia . 