Talking about languages

What word means "to use a lot of effort to defeat someone, prevent something, or achieve something"?

What word is missing?

She speaks six languages _______.

He has a strong ______, so he is __________ his pronunciation.

What does "accurate" mean?

They can ______ with their English knowledge.

Scars ________ us about that terrible accident.

Sorry, I didn't _______ your voice. Do you have a sore throat?

She wanted to send him a letter but couldn't _____ his address.

If you use this frequency, you'll be able to _______ it much faster.

Overall, music helps us _______ how we feel.