推测心绞痛发作时疼痛发生机制最可能是
A.电生理改变
B.心脏收缩功能障碍引起
C.多肽类刺激心脏内传入神经末梢
D.冠状血管痉挛引起
E.目前尚不清楚
参考答案:C
二次函数:y=x2+bx+c的图象经过点A(-1,0)、B(3,0)两点,其顶点坐标是______.
—How beautiful your skirt is !
—Thank you.It by my mom. [ ]
A. made
B. was made
C. makes
D. is made