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: Steroids were given to 39 % of patients for refractory rejection , but weaning was always attempted and generally successful ( 64 % ) .
### Output Text:
<span class="chemical">Steroids</span> were given to 39 % of patients for refractory rejection , but weaning was always attempted and generally successful ( 64 % ) . 