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: Five PMs were studied according to the same protocol , except for a higher terbutaline dose ( 0 . 75 mg ) on day 2 .
### Output Text:
Five PMs were studied according to the same protocol , except for a higher <span class="chemical">terbutaline</span> dose ( 0 . 75 mg ) on day 2 . 