물을 편하게 쓸 수 있도록 수로를 만들었습니다.
They developed waterways to use water conveniently.
감기에 걸렸을 때는 몸을 따뜻하게 해야 돼요.
You must keep your body warm when you catch a cold.
어제는 친구하고 재미있게 놀았어요.
I had fun playing with my friend yesterday.
선생님, 시험 문제를 쉽게 내세요.
Teacher, please make the test questions easy.
라디오를 크게 틀지 마세요.
Don't turn on the radio too loud.


(2) -로/으로 with, using, by means of
This marker is used to indicate the means with which someone performs an action, or by which someone drives or moves about.

옛날에는 흙으로 집을 만들었습니다.
Houses were made from soil in the old times.
그 책상은 나무로 만들었어요.
That desk is made out of wood.
한국음식은 숟가락과 젓가락으로 먹어요.
Spoons and chopsticks are used to eat Korean food.
집에서 학교까지 버스로 30분쯤 걸려요.
It takes about 30 minutes on the bus to get to school from home.
인터넷으로 한국말을 공부해요
I learn Korean from the Internet.


(3) -을 중심으로/를 중심으로
This form is used to express 'circling around,' 'near,' 'surrounding' something.

강 주변의 도시국가를 중심으로 문명이 생겨났습니다.
Ancient civilizations were born along the rivers as city-states.
책상을 중심으로 둥그렇게 앉으세요.
Sit around the desk please.
식탁에 케이크를 중심으로 음식을 놓으세요.
Circle the other dishes around the cake in the center.
태양을 중심으로 모든 별들은 태양 주위를 돌고 있습니다.
The other planets circle around the sun.
우리 집을 중심으로 오른쪽에는 빵가게가, 왼쪽에는 과일가게가 있어요.
With my house in the center, the bakery is on the right and fruit store is on the left.


(4) -아서/어서/해서 so, because
This form is used to indicate that the preceding clause is the reason or cause for the following clause. The final ending in the following clause cannot be either an imperative or propositive form.

사막과 바다로 둘러싸여서 다른 나라의 침입이 없었습니다.
Because it was surrounded by deserts and ocean, there was no foreign invasion.
공부를 열심히 해서 시험을 잘 봤습니다.
I did well on the exam because I studied hard.
약속에 늦어서 친구가 화가 났어요.
My friend was mad because I was late.
요즘 숙제가 많아서 놀 시간이 없어요.
I don't have time to play these days because I have a lot of homework.
그 책이 재미있어서 한 번 더 읽었습니다.
I read the book again because it was fun.