기는커녕 is used to indicate that not only is the content in the preceding clause not easily realized but also that the content in the following clause is even more so. Thus, the content of the following clause is usually more basic or simpler than that of the preceding clause. Usually, this expression takes the form of -기는커녕 도(조차) 안 -/못 -/없다.
가: 소희 씨, 오늘 생일이죠? 죽하해요. 아침에 미역국 먹었어요?
Sohee, isn’t today your birthday? Congratulations! Did you eat seaweed soup for breakfast?
나: 늦잠을 자는 바람에 미역국을 먹기는커녕 우유 한 잔도 못 마시고 나왔어요.
Due to oversleeping, I couldn’t even drink a glass of milk, let alone have some seaweed soup, before leaving the house.
가: 아이고, 저런. 그래도 저녁에는 남자 친구하고 만날거죠? 소희 씨를 깜짝 놀래 주려고 멋진 생일 파티를 준비했을 거예요.
Oh, dear, that’s terrible. But you’ll be meeting your boyfriend for dinner, right? I’m guessing he’s prepared a wonderful birthday party to really surprise you.
나: 생일 파티는요. 조금 전에 통화했는데 제 생일을 기억하기는커녕 바쁜데 왜 전화했냐며 짜증을 내더라고요.
A birthday party? We talked on the phone just a few minutes ago, and far from remembering my birthday, he was irritated that I had called (for seemingly no reason).
• 연우 씨가 선배를 보고 인사를 하기는커녕 못 본 체하고 그냥 가 버리더라고요.
Yeonwoo pretended not to see his superior, let alone greet her, and just walked away.
• 일찍 올 거라더니 일찍 오기는커녕 늦는다는 전화 한 통 없네요.
He said he’d come early, but he didn’t even call to say he’d be late, let alone come early.
• 내일이 시험인데 공부를 하기는커녕 TV만 보고 있어요.
The test is tomorrow, but he’s just watching TV, let alone studying.
• 열심히 공부했는데도 성적이 오르기는커녕 오히려 더 떨어졌어요.
Even though I studied hard, my grades have actually suffered, let alone gotten better.
1. When used with nouns, this expression takes the form of 은커녕/는커녕.
• 아침은커녕 점심도 아직 못 먹었어요.
• 요즘은 손님은커녕 문의 전화도 한 통 없어요.
2. With almost no change in meaning, -기는커녕 can be replaced with -는 것은 고사하고 while 은커녕/는커녕 can be replaced with 은/는 고사하고.
• 일찍 올 거라더니 일찍 오기는커녕 늦는다는 전화 한 통 없네요.
= 일찍 올 거라더 니 일찍 오는 것은 고사하고 늦는다는 전화 한 통 없네요.
• 아침은커녕 점심도 아직 못 먹었어요.
= 아침은 고사하고 점심도 아직 못 먹었어요.
>> You can click on the title of each grammar below to see other grammars which also express ‘Addition and Inclusion’
2. -기는커녕
3. -(으)ㄹ뿐더러
4. -되
5. 마저
6. -을/를 비롯해서
>> Full of ‘Korean grammar in use – Advanced’: Click here
>> Full of ‘Korean grammar in use – Intermediate’: Click here
I think your translations in to English were a bit hard to understand. For example: 열심히 공부했는데 성적이 오르기는 커녕 더 떨어졌어요. I think it should be "I studied hard but my grade wasn't improved EVEN it went down(lower than before)