How to make polite expressions (vs. casual way of expressions ) - 한국 존댓말 ( vs. 반말 )

Here're how you can distinguish between polite sentences and casual sentences. 

Polite expressions in statements Korean language  : ~요 ~ㅂ니다 (~합니다 ~습니다)

If the sentences end with ~요, ~ㅂ니다 (i.e., ~합니다 ~습니다), it is much formal and polite way of expressions in Korean language. 

Here're several sentences, you can study.

Hello : 안녕하세요 is much formal (polite) than  안녕. 

Hello : 반갑습니다. is much formal (polite) than 반가워.

Thank you : 고맙습니다 is much formal (polite) than 고마워.

It's sunny : 맑습니다 is much formal (polite) than 맑아.

It's okay/ I'm fine : 괜찮아요 is much formal (polite) than 괜찮아.

 

Polite expressions in questions Korean language  : ~요? ~ㅂ니까? (~합니까? ~습니까?)

Did you say that? : 그렇게 말했어요? is much formal (polite) than 그렇게 말했어?

Will you go? : 갈 것입니까? is much formal (polite) than 갈 거야?

Do you read? : 읽습니까? is much formal (polite) than 읽어?

Have you been to? : 간 적이 있습니까? is much formal (polite) than 간 적이 있어?

What time is it? : 몇 시입니까? is much formal (polite) than 몇 시야?