【多选题】假设检验中,有关“第一类错误”下面描述正确的是( )
【单选题】While some international couriers are showing signs of exhaustion, EMS (Express Mail Service), the generic name for the courier services of post offices, seems to be finding its stride. Known as Datap...
A.
problems of post offices in Britain
B.
the new courier service — EMS
C.
the competition between private and international courier services
D.
differences between EMS and DHL
【单选题】(2019•新课标III卷)下列实验不能达到目的的是( )
A.
【目的】制取较高浓度的次氯酸溶液;【实验】将Cl 2 通入碳酸钠溶液中
B.
【目的】加快氧气的生成速率;【实验】在过氧化氢溶液中加入少量MnO 2
C.
【目的】除去乙酸乙酯中的少量乙酸;【实验】加入饱和碳酸钠溶液洗涤、分液
D.
【目的】制备少量二氧化硫气体;【实验】向饱和亚硫酸钠溶液中滴加浓硫酸
【单选题】(2018•新课标III卷)下列实验操作不当的是( )
A.
用稀硫酸和锌粒制取H 2 时,加几滴CuSO 4 溶液以加快反应速率
B.
用标准HCl溶液滴定 NaHCO 3 溶液来测定其浓度,选择酚酞为指示剂
C.
用铂丝蘸取某碱金属的盐溶液灼烧,火焰呈黄色,证明其中含有Na +
D.
常压蒸馏时,加入液体的体积不超过圆底烧瓶容积的三分之二
【单选题】While some international couriers are showing signs of exhaustion, EMS (Express Mail Service), the generic name for the courier services of post offices, seems to be finding its stride. Known as Datap...
A.
problems of post offices in Britain
B.
the new courier service—EMS
C.
the competition between private and international courier services
D.
differences between EMS and DHL
【单选题】(2017•新课标III卷)下列说法正确的是( )
【简答题】丧主显在的消费动机的类型有()型、()型、()型、()型、()型、()型。