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: In addition , neither TET nor FAN showed any anticoagulation activities in the measurement of the activated partial thromboplastin time ( APTT ) , prothrombin time ( PT ) and thrombin time ( TT ) using human - citrated plasma .
### Output Text:
In addition , neither <span class="chemical">TET</span> nor <span class="chemical">FAN</span> showed any anticoagulation activities in the measurement of the activated partial thromboplastin time ( APTT ) , prothrombin time ( PT ) and thrombin time ( TT ) using human - citrated plasma . 