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: We propose that the paracetamol dose should not exceed 2 g / day in such patients and that their liver function should be monitored closely while being treated with paracetamol .
### Output Text:
We propose that the <span class="chemical">paracetamol</span> dose should not exceed 2 g / day in such patients and that their liver function should be monitored closely while being treated with <span class="chemical">paracetamol</span> . 