神经细胞每兴奋一次,膜内Na+浓度大约增加()
A.1/800
B.1/1000
C.1/8000
D.1/80000
E.1/800000
参考答案:D
升交点赤经是含地轴和春分点的子午面与()和升交点的子午面之间的交角。
It would be a good idea to use a plastic bottle, ___cut off, as a container to grow young plants in.
A.of which the top
B.the top is
C.the top of which
D.with its top