腕管综合征的病因是
A．正中神经在腕管内受压B．桡神经在腕管内受压C．桡动脉在腕管内受压D．尺动脉在腕管内受压E．尺神经在腕管内受压
参考答案：A
My mother is ill. I __________ stay at home to take care of her.[ ]
A. can
B. may
C. should
D. maybe
三个阻值都为R的电阻，它们任意连接、组合，得到的电阻值可能是( )
A．0.5R
B．4R
C．1.5R
D．1R
