9. Astronomers at the Palomar Observatory have discovered a distant supernova explosion, one that they believe is a type previously unknown to science.
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 这里的that多余,应该是believe to do sth
(B)that they believe it to be 这里的that多余,it 多余
(C)they believe that it is of believe that 用法错误
(D)they believe that is believe that 用法错误
(E)they believe to be of believe to do sth 结构对,of其限制作用,