黄体酮分子结构中具有:()
A. α-醇酮基
B. 酚羟基
C. 甲酮基
D. 氨基嘧啶环
E. 内酯环
在安装有孔板流量计的管道上再增加哪种仪表就可以测质量流量,原理是什么?
Later on, I will give an ___ to illustrate this point.
A. instance
B. example
C. case
D. template
I ____ Bob yesterday on main street.
A. ran after
B. ran against
C. ran into
D. ran away