8892
The modified monomers designed for these studies all share a common feature , they lack the naturally occurring 3 ' - hydroxyl group found in 2 - deoxyribonucleosides .
 Chemical: 3 ' - hydroxyl; Chemical: 2 - deoxyribonucleosides
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: 3 ' - hydroxyl; Chemical: 2 - deoxyribonucleosides