—Do you think it is hard for you to learn math well?

—Yes. I really want to drop it.

A．go on learning well

B．pick it up

C．give it up

D．work hard at it

在脊髓部位通直流电时，如阳极置于上端，阴极置于下端，下列反应哪项除外（）。

A.加速上肢和肺的静脉回流

B.降低血压

C.降低肌张力

D.使血沉加速

E.加速血液自肺循环回心