预防尿酸盐结石可服用（）
A.氧化镁或维生素B6
B.氯化铵
C.碳酸氢钠
D.氯化钾
E.别嘌呤醇
参考答案：C
— I don't think this TV set is of good quality. Can you replace it with a new one?
— _____. But I have to talk to my manager first. [ ]
A. I'm sorry
B. No way
C. No problem
D. That's a question
一闭合线圈置于磁场中，若磁感应强度B随时间变化的规律如图所示，则图中能正确反映线圈中感应电动势E随时间t变化的图象是（ ）
A．
B．
C．
D．
