计算:a3•a4等于( )
A.a7
B.a12
C.3a4
D.4a3
a3•a4=a7.
故选A
After studying in a medical college for five years, Jane ______ her job as a doctor in the countryside.
A.set out
B.took over
C.took up
D.set up
多发性硬化的临床症状可表现在以下哪些方面()
A.精神症状
B.脑神经功能障碍
C.运动功能障碍
D.感觉障碍
E.膀胱功能障碍或肠道功能障碍