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: RESULTS : Testosterone was less than 3 ng . / ml . in 107 patients but normal in 40 % at repeat determination .
### Output Text:
RESULTS : <span class="chemical">Testosterone</span> was less than 3 ng . / ml . in 107 patients but normal in 40 % at repeat determination . 