He spoke so softly that nobody could hear him. Which part of speech is the underlined word?

1.The old man spoke in a harsh voice. Which part of speech is the underlined word?

2.Although it rained, the match continued. Which part of speech is the underlined word?

3.He is good ___ mathematics.

4.She is interested ___ learning Japanese.

5.The proposal was rejected ___ grounds of insufficient data.

6.Which is the correct sentence?

7.Identify the correct sentence.

8.Despite the manager's calm tone, his email carried a subtle note of _____, warning the staff $\to meet the$ deadline.

9.The scientist's theory was dismissed as _____ until new evidence proved it correct.

10.Her speech was so full of unnecessary details that it became a long _____ on minor issues.

11.The new intern was surprisingly _____, quickly adapting $\to the fast-paced work$ environment.

12.The idiom “spill the beans” means —