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: No hepatic preneoplastic nodules or hepatocellular carcinomas developed in rats fed the plain choline - supplemented diet , while one preneoplastic nodule and one hepatocellular carcinoma developed in two rats fed the same diet containing phenobarbital .
### Output Text:
No hepatic preneoplastic nodules or hepatocellular carcinomas developed in rats fed the plain <span class="chemical">choline</span> - supplemented diet , while one preneoplastic nodule and one hepatocellular carcinoma developed in two rats fed the same diet containing <span class="chemical">phenobarbital</span> . 