V/A+ 었다면/았다면/였다면 V+ 을/ㄹ 수 없었겠지요?

It is used to mention a fact that became possible due to an event or situation that happened in the past. You assume the past situation in the opposite way by using ‘-었다면/았다면/였다면’ in the preceding clause. In the following clause, you should attach ‘-을/ㄹ 수 없었겠지요?’ after the stem of an action verb to ask back while assuming the opposite result of the present fact.

스마트폰이 없었다면 지금처럼 자유롭게 인터넷을 사용할 수 없었겠지요?
Without smartphones, we couldn’t have been able to use the internet as freely as we do now, could we?

만약 그 수술이 실패했다면 제가 지금처럼 건강하게 살 수 없었겠지요?
If the surgery had failed, I wouldn’t have been able to live as healthy as I am, am I?

지난 학기에 열심히 공부하지 않았다면 장학금을 받을 수 없었겠지?
If I hadn’t studied hard last semester, I wouldn’t have gotten a scholarship, would I?

Conversation:

앗, 따가워. 겨울철에는 정전기 때문에 너무 불편해. 정전기가 없는 세상에서 살고 싶어.
Oh, it stings. I feel so uncomfortable in winter because of static electricity. I want to live in a world without static electricity.

그럼 스마트폰도 지금처럼 편리하게 사용할 수 없었을 텐데?
Then you couldn’t have used your smartphone as conveniently as you do now?

스마트폰이 정전기하고 상관있어?
Do smartphones have anything to do with static electricity?

스마트폰 화면은 터치스크린을 사용하는데 터치스크린은 우리 몸의 미세한 정전기를 감지해서 입력하는 방식이야.
A touchscreen is used for a smartphone, and it uses a way of detecting our body’s tiny static electricity to input a signal.

불편한 줄만 알았던 정전기가 이렇게 활용되는구나.
The static electricity that I thought to be inconvenient is being utilized like that.

응, 정전기가 없었다면 이렇게 편리한 터치스크린을 사용할 수 없었겠지?
Yes, without static electricity, we couldn’t have been using such a convenient touchscreen, wouldn’t we?

Related words
정전기 static electricity
상관있다 to have something to do with
터치스크린(touchscreen) touchscreen
미세하다 to be fine
감지 detection

Source: Yonsei University. Korean Language Institute