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: Twelve healthy volunteers were assigned to take BPT / CLZ in the following schedule ; BPT : 40 micrograms at day 1 and 120 micrograms t . i . d . from day 7 to 14 , CLZ : 200 mg t . i . d . from day 3 to 14 .
### Output Text:
Twelve healthy volunteers were assigned to take <span class="chemical">BPT</span> / <span class="chemical">CLZ</span> in the following schedule ; <span class="chemical">BPT</span> : 40 micrograms at day 1 and 120 micrograms t . i . d . from day 7 to 14 , <span class="chemical">CLZ</span> : 200 mg t . i . d . from day 3 to 14 . 