不采用煮法炮制的药物
A.川乌
B.吴茱萸
C.珍珠
D.杏仁
参考答案：D
函数f（x）=（a-2）x2+2（a-2）x-4，a∈R
（1）若x∈R，f（x）＜0恒成立，求a的取值范围；
（2）若x∈[1，3]时，f（x）＜0恒成立，求a的取值范围．
People in China don't often kiss or hug each other goodbyes or hellos, which ______ a common _______ in some European countries. [ ]
A. are; practice
B. is; exercise
C. are; exercise
D. is; practice
