have you ever heard this opera sung in italian?

여기서 have you ever p.p 로 heard 인건가요 ??

그런데 왜 sung 을 쓰죠 ??

이탈리아에서 노래된 이란 뜻이라서 수동태인가요 ??

그리고 하나더

밑줄친 문장의 쓰임새가 다른것은? it is true that i like clothes.

1)it is a lie that he loves you .(다 that에 밑줄이에요)
2)it is clear that he loves his children very much
3)it is a snake that he is afraid of
4)it surprised me that he has gone to europe
5)it is dangerous that children play in the middle of the road.

여기서 답이 3번 이라고하는데

3번이 관계대명사 (목적격)이고 나머지는 다 접속사 that 인가요??
알려주세요 ㅠ ㅠ 헬프헬프