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: Angioedema due to ACE inhibitors : common and inadequately diagnosed .
### Output Text:
Angioedema due to <span class="chemical">ACE inhibitors</span> : common and inadequately diagnosed . 