In the sentence, the verb "properly" is used to describe how the action of grinding the beans was performed. The correct form of the verb "grind" to use with "properly" is "ground."
Here's why "ground" is the correct choice:
- "Grind" is the base form of the verb, used in the present tense (e.g., "I grind the coffee beans every morning").
- "Ground" is the past participle form of the verb, used to form the past tense and past perfect tense (e.g., "I ground the coffee beans yesterday" or "I have ground the coffee beans before").
In the sentence "The beans have not been properly ground," "ground" is the past participle form of "grind" and is used because the action of grinding the beans happened in the past and is completed.