쌤 질문있습니다......
 our friends are expected to assume the burden of their own defense,__________ they are competent to do.

 a)which we are certain b)that we are certain of
 c)of which we are sure d)for which we are sure

여기서 정답이 a인데 다른건 왜 틀렸는지 잘 모르겠습니다.
제가 워낙 초보라서...........

we are given just so much food _______will keep the breath in our bodies.
 a)as b)that
 c)what d)but

이문제는 b가답이라고 생각했는데 a가 답이네여.....
정말 잘 모르겠네여..........흑흑

 오늘 수업을 첨 들어서 저번 시강에 했던 강의 내용을 잘 모르겠습니다^^:
쌤 건강하세여............