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【单选题】
吗啡易被氧化变色是因为分子结构中含有的基团是()A.
醇羟基
B.
醚键
C.
酚羟基
D.
哌啶环
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参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【简答题】开标应当在招标文件确定的提交投标文件截止时间的()公开进行;开标地点应当为招标文件中预先确定的地点。
【单选题】The bus driver came back to the author because __________ .
A.
the bus was out of service
B.
she had no lighted number
C.
she wanted to help the author to the end
D.
she wanted to take the author to another bus
【单选题】The coastguards came out to help the author because
A.
they discovered the author capsized his catamaran.
B.
the author encountered a big whale.
C.
they had lifesaving obligation.
D.
they were well-meaning people.
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