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: Of the 714 creatine phosphokinase levels , 9 % were high ; only 1 ( 0 . 1 % ) was greater than or equal to 3 times the upper normal limit .
### Output Text:
Of the 714 <span class="chemical">creatine</span> phosphokinase levels , 9 % were high ; only 1 ( 0 . 1 % ) was greater than or equal to 3 times the upper normal limit . 