下列关于神经纤维膜上电压门控Na+通道与K+通道共同点的描述，错误的是
A．都有开放状态B．都有关闭状态C．都有激活状态D．都有失活状态
参考答案：D
The road was so narrow that there would be traffic jams____, especially during the rush hour.
A．every now and then
B．more or less
C．from then on
D．up and down
深度为5的满二叉树有______个叶子结点。
