In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

Example Input: Some school boards have _ teacher-librarians at all.
Example Output: no

Example Input: Liquids usually descend in three to five seconds, and solids in _ to twenty seconds.
Example Output: eight

Example Input: Biological information is replicated as the _ strands are separated.
Example Output:
two