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【单选题】
下列化学实验中的操作错误的是( )A.
蒸馏和回流实验中用循环冷却,连接管路的橡胶管必须接牢,而且应时常检查是否老化或容易脱落
B.
使用明火加热低沸点易燃溶剂。
C.
进行蒸馏和回流操作时,务必防止形成封闭体系。
D.
不同的溶剂体系采用不同的加热方式,例如沸点在80℃以下的乙醚、二硫化碳、丙酮等溶剂宜用水浴加热,而且只能从冷水开始加热。
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皮皮学刷刷变学霸
举一反三
【单选题】Directly he saw her, he fell ______ in love.
A.
from head to foot
B.
head over heels
C.
head and shoulders
D.
toe to toe
【单选题】I do believe that ______ swim across the river, but, in that situation, I ____ do that.
A.
am able; couldn’t
B.
could; was able to
C.
was quite able to; couldn’t
D.
couldn’t was able to
【简答题】4. Seldom do I have seen a
situation which made me so angry.
【简答题】He really did nothing practical, for he ____________ (不是看电视就是睡觉).
【单选题】When Fredy told Pearman to call if he was serious, he meant if ______.
A.
Pearman was really hardworking
B.
Pearman was really looking for a job
C.
Pearman's conditions were truly serious
D.
Pearman was really interested in washing windshields
【简答题】Seldom do I have seen a situation which made me so angry. __________________________________________________________.
【简答题】Look at the terrible situation I am in! If only I ________ your advice. A) had followed B) would follow C) follow D) have followed
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