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参考答案：
参考解析：
刷刷题刷刷变学霸
举一反三
【单选题】在半导体材料中,其正确的说法是( )
A.
P型半导体中由于多数载流子为空穴，所以它带正电
B.
N型半导体中由于多数载流子为电子，所以它负正电
C.
P型和N型半导体材料本身都不带电。
D.
以上说法都不正确
【单选题】Human beings have used tools for a very long time. In some parts of the world you can still find tools that people used more than two million years ago. They made these tools by hitting one stone agai...
A.
disastrous.
B.
unpredictable.
C.
exciting.
D.
colourful.