9. Astronomers at the Palomar Observatory have discovered a distant supernova explosion, one that they believe is a type previously unknown to science. (A) that they believe is (B) that they believe it to be (C) they believe that it is of (D) they believe that is (E) they believe to be of 这道题我选的是C 我知道believe有两种用法 OG上好象是说C中的that it 不符合语法现象 不太明白什么意思. 而且新东方老师说宾语从句中的that不能省略 这对吗?谢谢指点