（）有限流作用。
A.负温度系数热敏电阻
B.功率热敏电阻
C.临界温度系数热敏电阻
D.正温度系数热敏电阻
参考答案：D
. Research findings show we spend about two hours dreaming every night, no matter what we ____ have done during the day.
A．should
B．would
C．may
D．must
纳税人外购货物因管理不善丢失的，该外购货物的增值税进项税额不得从销项税额中抵扣。（ ）
