二尖瓣狭窄时下列哪种处理不恰当()
A.保持体循环阻力
B.降低肺循环阻力
C.适当增加前负荷
D.增加心率
E.尽量少用正性肌力的药物
参考答案:D
So _____ that all the living things died out gradually .
A.serious polluted the lake is
B.serious polluted is the lake
C.seriously polluted the lake is
D.seriously polluted is the lake
如图所示,一个静止质量为m,带电量为+q的带电粒子(不计重力),经电压为U的电场加速后垂直进入磁感应强度为B的匀强磁场中,并打在P点。设OP=x,能正确反映x与U之间函数关系的x-U图象如图中的
A.
B.
C.
D.