난 두 숟갈의 설탕을 넣는다.- I put in two spoons of sugar. ​or I add two spoons of sugar.

​- 나의 아버지는 잔디를 깎았다.  My father mowed a lawn.

- 난 좀 쉴 거야.  I'm going to rest for a while.

Which of the following is correct in English? DD/MM/YY, MM/DD/YY. ("YY/MM/DD" is common in Korean)

- In this case, all of the DATE FORMATS are correct. It simply depends on which of the date formats is generally used in each country. 

Here in my country, we commonly used MM/DD/YY.