A. BUY
Example:
I need to go to the supermarket to buy some groceries.
Meaning:
Purchase
Form:
Verb
B. BY:
Example 1:
She likes to sit by the window.
Meaning:
Close to
Form:
Preposition of place
Example 2:
I and my friend get in touch by e-mails.
Meaning:
How to do something
Form:
Preposition:
Example 3:
They had slept by midnight.
Meaning:
Before
Form:
Preposition of time
C. BYE:
Example:
Bye. See you soon.
Form:
Exclamation
Meaning:
farewell