题干
_____ he was very tired, he continued working in his office.
A：Since
B：Although
C：As soon as
D：Because
答案(点此获取答案解析）
B
_____ he was very tired, he continued working in his office.
A：Since
B：Although
C：As soon as
D：Because
）是最常见的消炎解热镇痛药，用于治疗感冒发烧和关节痛等．M的一种合成路线如下： 
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