-군요

V/Adj/이다,아니다 + (는)군요

When the speaker pays attention to a new fact and learns through seeing or hearing. It often has the meaning of exclamatory.

• When speaking informally, remove ‘-요’ and use ‘-군’, or you can use ‘-구나’ instead. Since it's an expression of exclamation to oneself, the informal form ‘-구나’ is more commonly used in actual conversations (’-구나요’ form doesn't exist).

집이 좀 더럽군. = 집이 좀 더럽구나.
 
인테리어가 정말 특이하구나!
Wow, the interior design is really unique!

• 네요 VS 군요

네요	군요
When you are expressing amazement directly to the listener after realizing something from witnessing a scene. 닝닝 씨 집이 정말 아름답네! → feels like the speaker trying to continue the conversation with Ningning by complimenting her.	When you are expressing amazement to yourself. 닝닝 씨 집이 정말 아름답군! → feels like the speaker nodding to oneself while reflecting on something newly realized.
It can only be used about facts that the speaker has directly experienced or facts that have clear evidence. (after eating) 약이 너무 쓰네요 O (without eating) 약이 너무 쓰네요 X	It can be used not only for things directly experienced by the speaker but also for facts learned from others or derived through reasoning. (after eating) 약이 너무 쓰군요 O (without eating) 약이 너무 쓰군요 O
It can’t be used with ‘-니까’, ‘-어서’ 토니 씨는 운동을 많이 하니까 키가 크네요 X	It can be used with ‘-니까’, ‘-어서’ 토니 씨는 운동을 많이 하니까 키가 크군요 O

• Verb

Root + 는군(요), 는구나

ex. 가는군, 먹는군

• Adjective, 이다/아니다, -었-, -겠-

Root + 군(요), 구나

ex. 예쁘군, 덥군, 멀군, N+ (이)군/아니군 갔군, 가겠군, 예뻤군, 예쁘겠군, 있군(재밌군요, 맛있군)

1. 벌써 다섯 시다 + (는)구나 →

2. 어제 눈이 많이 왔다 + (는)군요→

3. 이게 그 유명한 비빔밥이다 + (는)구나 →

4. A: 수지 씨 집은 서울에 있어요.
B: 그렇다

5. A: 여기는 제 아내입니다.
B: 두 분이 결혼하셨다

6. A: 나 다음 주에 음악 페스티벌 갈 거야.
B: 너도 가다 !