山莨菪碱治疗休克的机制主要是
A．阻断M受体B．增加心率C．舒张血管D．升高血压E．兴奋中枢
参考答案：C
----So you’ve got the news?
----Yes, but I’d rather I _______.
A．hadn’t told about it
B．didn’t tell about it
C．were not told about it
D．hadn’t been told about it
频率特性是系统对（）的稳态响应。
A.正弦输入
B.余弦输入
C.阶跃输入
D.脉冲输入
