从血流动力学角度,血压主要取决于()
A.心肌收缩力
B.体循环周围血管的阻力
C.心排出量
D.以上均是
E.血容量
参考答案:B, C
I ______ with a classmate of mine because my parents have gone abroad on business.[ ]
A. stayed
B. am staying
C. have stayed
D. was staying
零序电流保护由哪几部分组成()
A、零序电流滤过器
B、电流继电器
C、零序方向继电器
D、电压继电器