[单选题]Directions: In this part there is a sentence with four choices marked A, B, C and D. Choose the one that best completes the sentence. The government is determined to spare no effort in investigating this case（ ）.
A
frequently
B
thoroughly
C
permanently
D
intentionally
正确答案：B
题目解析
本题考查常见副词的词义辨析。 frequently：经常地，thoroughly：彻底地，permanently：永久地，intentionally：故意地。spare no effort in doing sth是固定搭配意为“不遗余力地做某事”，分析语境，政府决定不遗余力地调查这个案子…。由“不遗余力地”可知，此处“彻底地”含义最符合语境，故选B。 句意：政府决定不遗余力地彻底调查这个案子。
