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: A range of strain specific sensitivities was documented with A / J and SJL mice being most sensitive and C57BL / 6J most resistant .
### Output Text:
A range of strain specific sensitivities was documented with A / J and SJL mice being most sensitive and C57BL / 6J most resistant . 