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【单选题】
取阿司匹林10片(每片0.1克),精密称定,研细,精密称出适量(约相当于阿司匹林0.3g),置锥形瓶中,加中性乙醇(对酚酞指示液显中性)20ml,振摇,使阿司匹林溶解,加酚酞指示液3滴,滴加氢氧化钠滴定液(0.1mol/L)至溶液显粉红色,再精密加氢氧化钠滴定液(0.1mol/L)40ml,置水浴上加热15分钟并时时振摇,迅速放室温,用硫酸滴定液(0.05mol/L)滴定,共消耗硫酸滴定液15ml, 并将滴定的结果用空白试验校正,共消耗硫酸滴定液30ml。每1ml氢氧化钠滴定液( 0.1mol/L )相当于18mg乙酰水杨酸。 阿司匹林的百分含量是( )%。A.
80
B.
60
C.
90
D.
100
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举一反三
【单选题】—Is the old woman ________? —Yes, but she doesn't feel ________. [ ]
A.
lonely; alone
B.
lonely; lonely
C.
alone; alone
D.
alone; lonely
【单选题】Although some old people live near their sons or daughters, ______.
A.
they still feel lonely
B.
they want to move to other places
C.
they have no time to look after the young people's children
D.
they like to live with their own brothers and sisters
【简答题】a____ vt. ( fml. ) give sb. information about sth. 介绍;使认识;使了解
【单选题】We need friends to ________, or we will feel ________.
A.
chat, alone
B.
chat with, lonely
C.
speak, lonely
D.
talk with, alone
【简答题】vt. (fml.) give sb. sth. or allow them to have sth. that they have asked for 给予;准予n. [C] an amount of money given to sb., esp. by the government, for a particular purpose (尤指政府发给的)补助金,拨款
【单选题】－How do you do? －_____. [ ]
A.
Hello.
B.
How are you?
C.
How do you do?
D.
I'm fine, thank you
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