TTL与非集成门电路输出为高电平时，则输入端（）为低电平。
A、全
B、全不
C、至少有1个
D、至少有1个不
参考答案：C
航空运输一般按照货物的实际重量(千克)和体积重量(以6000立方米或366立方英寸体积折合1千克)两者之中较高者来计运费。
Not every prisoner can travel, and we have strict and fair regulations. Those selected ______ have
performed well in the prison and are going to be released soon.[ ]
A. could
B. might
C. must
D. should
