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: Rapid reversal of life - threatening diltiazem - induced tetany with calcium chloride .
### Output Text:
Rapid reversal of life - threatening <span class="chemical">diltiazem</span> - induced tetany with <span class="chemical">calcium chloride</span> . 