具有镇痛作用的成分是（）
A.栀子苷
B.番泻苷A
C.茵陈黄酮
D.乌头碱
E.麻黄碱
参考答案：D
— According to my grandma, it is a good idea to eat chicken soup when you have a cold.
— _____, scientists agree with her.[ ]
A. Sooner or later
B. Once in a while
C. To be exact
D. Believe it or not
什么是队形变换？队形变换的原则是什么？
