The new manager has greatly changed the company __________ he took over the position.
选择一项：
a. while
b. since 解析：本句意思为：“自从新的经理接管这个职位，公司有了很大的变化”。本题考查状语从句连词的用法。if：如果; since：从…以后；although：虽然，尽管；while：当…的时候。根据句子意思，正确答案为B。
c. although
d. if