he was not rich enough to buy whatever he wanted, Edison decided to make his new laboratory the best.
A. Although
B. Since
C. When
D. As
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(答案→)A. Although
B. Since
C. When
D. As
解析：连词辨析。Although虽然，尽管；Since 因为，由于；When当……时候；As
虽然，尽管。句子前后表让步关系，排除B,C；as引导让步状语从句，句子需要倒装，而原句的正常语序，所以排除D；选A。