다음 글을 읽고, 물음에 답하시오.[1~5]

ⓐ People believe that kimchi first appeared on the Korean Peninsula some 3,000 years ago. As fresh vegetables were too hard to ⓑ come by during the cold winter, it was necessary to find ways to preserve them until spring came. Pickling them in salt was one such way people found. Diggings from the Three Kingdom Period (4th to 7th century) suggest that vegetables kept in salt existed almost 1,500 years ago. Large jars made earth are often dug up on the peninsula. They measure some 90 centimeters in height and 220 centimeters around the middle, large enough to store vegetables in salted water. On one jar was written: A family of ten needs eight jars to make it through the winter.

01 위 글의 주제로 알맞은 것은?

① 김치의 효능 ② 김치의 역사

③ 김치의 원리④ 김치 저장 용기

⑤ 김치 만드는 방법

02 밑줄 친 ⓐ를 다음과 같이 수동태 문장으로 바꿀 때 빈칸에 알맞은 말은?

It that kimchi first appeared on the Korean Peninsula some 3,000 years ago.