词汇与结构The weather is __________, which was sunny in the morning, but gloomy now.
A. bad
B. unusual
C. fair
D. unpredictable
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词汇与结构Aviation service units offer pilots weather information gathering from __________.
A. meteorological authorities
B. aviation authorities
C. flight authorities
D. ATC authorities
具有吗啡结构的镇痛药有
A. 阿司匹林
B. 阿扑吗啡
C. 纳洛酮
D. 美沙酮
具有氨基酮结构的镇痛药
A. 吗啡
B. 美沙酮
C. 哌替啶
D. 芬太尼
镇痛药杜冷丁属于
A. 氨基酮类
B. 哌啶类
C. 吗啡烃类
D. 苯吗喃类
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