아

1. -a
A connective ending used when the preceding statement happened before the following statement or was the ways or means to the following statement.

2. -a
A connective ending used when the preceding statement is the cause or reason for the following statement.

3. -a
A connective ending used to connect a verb and adjective with such auxiliary predicate elements as '두다,' '버리다,' '보다,' '있다,' and '주다.'

4. -a
(informal addressee-lowering) A sentence-final ending used to describe a certain fact, ask a question, give an order, or advise.