若使用1种生物碱沉淀试剂进行鉴别显示出阳性，则可证明该物质中含有生物碱
A. 对
B. 错
若生物碱沉淀试剂未显阳性，则说明该物质中不含生物碱
A. 对
B. 错
根据以下句子，选出最符合句意的一个单词The party has threatened to______the election becauseit believes it will not bedemocratic.
A. ban
B. boycott
C. veto
D. refuse
This passage mainly tells us about:
A. The quality of one's life is what is important.
B. Dr. King was awarded the 1964 Nobel Peace Prize.
C. Dr. King fought for civilrights all his life.
Dr. King led a bus boycott in Alabama.
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