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: Visual analogue scores ( mean + / - SD ) during induction were lower in Groups L ( 3 . 3 + / - 2 . 5 ) and T ( 4 . 1 + / - 2 . 7 ) than in Group C ( 5 . 6 + / - 2 . 3 ) ; P = 0 . 0031 .
### Output Text:
Visual analogue scores ( mean + / - SD ) during induction were lower in Groups L ( 3 . 3 + / - 2 . 5 ) and T ( 4 . 1 + / - 2 . 7 ) than in Group C ( 5 . 6 + / - 2 . 3 ) ; P = 0 . 0031 . 