理想电压源与理想电流源（）进行等效变换。
A、能够
B、不能够
C、不确定
D、一般情况下能够
参考答案：B
The study of nearly 10,000 people showed that those who drank more than two cups of coffee or tea per day developed the disease at half the rate of those who drank _________ than one cup each day.
A．little
B．less
C．more
D．fewer
根据国家标准《危险货物分类和品名编号》（GB6944—86）和《危险货物品名表》（GB12268—90）的规定，危险物品分为（）大类。
A、六
B、七
C、八
D、九
