--- You didn’t come to school by bike today, did you?

---     .It’s broken.

A．Yes, I did

B．No, I didn’t

C．Yes, I didn’t

D．No, I did

利血平的降压机制是（）

A.抑制血管运动中枢

B.激动延脑孤束核抑制性神经元突触后膜的α₂R

C.直接舒张血管平滑肌

D.激动外周AD能神经元突触前膜α₂R

E.耗竭去甲肾上腺系能神经末梢递质