TASK DEFINITION: In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
PROBLEM: Diatoms look like _ shells that fit together.

SOLUTION: two

PROBLEM: Terrorism is a problem which has troubled the international community for more than _ decades.

SOLUTION: three

PROBLEM: Manatees are herbivorous animals and spend _ to eight hours a day eating.

SOLUTION:
six