An investigation that is ---------- can occasionally yield new facts, even notable ones, but typically the appearance of such facts is the result of a search in a definite direction.
(A) timely
(B) unguided
(C) consistent
(D) uncomplicated
(E) subjective
〖解答〗
在以but连接的两个句子中分别两次涉及“研究”(investigation search)这一概念。从search后面的介词结构in a definite direction可求取其反义词(B) unguided。