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: This double - blind , randomized , placebo - controlled study evaluated the effects of haloperidol alone and haloperidol plus sertraline on cognitive and psychomotor function in 24 healthy male subjects .
### Output Text:
This double - blind , randomized , placebo - controlled study evaluated the effects of <span class="chemical">haloperidol</span> alone and <span class="chemical">haloperidol</span> plus <span class="chemical">sertraline</span> on cognitive and psychomotor function in 24 healthy male subjects . 