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: We have investigated the effects of continuous daily oral galactose ( 200 mg / kg / day ) treatment on cognitive deficits in streptozotocin - induced ( STZ - icv ) rat model of sAD , tested by Morris Water Maze and Passive Avoidance test , respectively .
### Output Text:
We have investigated the effects of continuous daily oral <span class="chemical">galactose</span> ( 200 mg / kg / day ) treatment on cognitive deficits in <span class="chemical">streptozotocin</span> - induced ( <span class="chemical">STZ</span> - icv ) rat model of sAD , tested by Morris Water Maze and Passive Avoidance test , respectively . 