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: The actions of fenoterol - hydrobromide , ritodrin - HCl and placebo given to 10 healthy subjects by intravenous infusion in a double - blind crossover study were tested by this method .
### Output Text:
The actions of <span class="chemical">fenoterol - hydrobromide</span> , <span class="chemical">ritodrin - HCl</span> and placebo given to 10 healthy subjects by intravenous infusion in a double - blind crossover study were tested by this method . 