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【单选题】
可以将培养的细胞较长时间冷冻保存在( )中,待研究需要细胞复苏后再培养。A.
-196℃液氮
B.
-80℃
C.
-20℃
D.
4℃
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【简答题】A．John's house was burned down. B．John finally got rid of his shoes. C．John lost his intelt dog. D．John got into trouble with his neighbor.
【单选题】John ______stop his car in time, so he hit the girl.
A.
could
B.
can
C.
can’t
D.
couldn’t
【单选题】John hadn’t been able to stop smoking suddenly;he had to control his smoking desire ________.
A.
by and by
B.
sooner or later
C.
little by little
D.
from time to time
【单选题】—Is John coming by train? —He should, but he ______not. He likes driving his car.
A.
must
B.
can
C.
need
D.
may
【简答题】二轴晶光性符号的确定是根据:当( )正光性,当( )负光性; 具有两个光轴的晶体属于( )、( )、( )晶系; 在宝石的肉眼鉴定中,通常将宝石的透明度大致划分为:_____、_____、_____、_____、_____五个级别。 光泽越强的宝石色散越强; 色散强的宝石,其双折射率一定也高;
【简答题】John ( ) stop his car in time, so he hit the girl.
【单选题】Why did George stop his car?
A.
The traffic light was red.
B.
Something went wrong with his car.
C.
He wanted to speak to the boy and his girlfriend.
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