下列化合物与苯进行傅-克烷基化反应,有重排产物的是()。
A. 一氯甲烷
B. 一氯乙烷
C. 2-甲基-2-氯丙烷
D. 一氯丙烷
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以下化合物为碱的是( )。
A. HBr
BF3
C. NH3
D. HCOOH
以下化合物或离子为碱的是( )。
A. HCl
B. AlCl3
CN-
D. NH4+
Which one is not semiconductor microwave device.( )
A. Tunnel Diode
B. GUNN Diode
C. IMPATT Diode
D. Photodiode
Which one is not the characteristics of power transistor.( )
A. The relatively wide base width implies a much smaller current gain β
B. Large area device implies a larger junction capacitance
C. The current gain is generally smaller in the power transistors
D. Large area device increases the cutoff frequency
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