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: The most common regimens were 3TC + d4T + nevirapine ( NVP ) ( 54 . 8 % ) , zidovudine ( AZT ) + 3TC + NVP ( 14 . 5 % ) , 3TC + d4T + efavirenz ( EFV ) ( 20 . 1 % ) , and AZT + 3TC + EFV ( 5 . 4 % ) .
### Output Text:
The most common regimens were <span class="chemical">3TC</span> + <span class="chemical">d4T</span> + <span class="chemical">nevirapine</span> ( <span class="chemical">NVP</span> ) ( 54 . 8 % ) , <span class="chemical">zidovudine</span> ( <span class="chemical">AZT</span> ) + <span class="chemical">3TC</span> + <span class="chemical">NVP</span> ( 14 . 5 % ) , <span class="chemical">3TC</span> + <span class="chemical">d4T</span> + <span class="chemical">efavirenz</span> ( <span class="chemical">EFV</span> ) ( 20 . 1 % ) , and <span class="chemical">AZT</span> + <span class="chemical">3TC</span> + <span class="chemical">EFV</span> ( 5 . 4 % ) . 