COULD

Could is an auxiliary verb, a modal auxiliary verb. 

We use could to:

• Talk about past possibility or ability
• Example: I could basketball when I was 10 years old.

• make requests in a formal way

Examples:

• Could you repeat, please?
• Could you send me a letter, please?

WOULD YOU LIKE HOW TO IMPROVE YOUR VOCABULARY?

First you should practice by a set of words or family words:
Example:
LANGUAGES

• Spanish
• English
• French
• Japanese
• Arabic