145. 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）
(E) they believe to be of
e ETS explains that "since the pronon one is sufficient to introduce the modifier and the sentence is more flued without that" BY chapter 2 says"同位语从句是有one that……“
那究竟要不要省略that 呢？
同例
1. The proposed urban development zones do not represent a new principle; it was employed in “Operation Bootstrap” in Puerto Rico.
(A) do not represent a new principle; it
(B) represent not a new principle, but one that
(C) are not a new principle; the same one
(D) are not a new principle, but one that（B）
(E) are not new in principle; it
B
1. The science of economics, which for four decades was dominated by Keynesians, who at first stressed the government’s role in stimulating the economy, but who were ultimately led away from solutions based on government intervention.
(A) economics, which for four decades was
(B) economics that was to be
(C) economics, one which has, for four decades, been
(D) economics is one that for four decades has been（D）
(E) economics, for four decades, is one that was
d | 
