欧姆定律公式可以表明，流过电阻的电流与电阻两端的电压（）.
A.成正比
B.成反比
C.无关
D.关系变化无规律
参考答案：B
----- Have you informed Tom and Ann that some foreign experts will visit our company at 8:00 tomorrow morning?
------ Yes, I have. But_____ of them asked me to tell you that they would not be able to come.
A．any
B．either
C．both
D．two
组合设计：
