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: Recovery room discharge times were similar : C ( 75 . 9 + / - 19 . 4 min ) ; L 73 . 6 + / - 21 . 6 min ) ; T ( 77 . 1 + / - 18 . 9 min ) .
### Output Text:
Recovery room discharge times were similar : C ( 75 . 9 + / - 19 . 4 min ) ; L 73 . 6 + / - 21 . 6 min ) ; T ( 77 . 1 + / - 18 . 9 min ) . 