哺乳动物的子代成活率大大提高,其主要原因是 [ ]
A.体表有毛
B.大脑发达
C.胎生和哺乳
D.活动范围广
答案:C
动作电位沿神经纤维到达神经肌接头时,使终板膜产生终板电位,然后在什么部位引发动作电位()
A.肌细胞膜
B.接头后膜
C.横管膜
D.三联管膜
E.终板膜
You've never heard ______ this new kind of plane, ______ you?[ ]
A. / ; haven't
B. of ; haven't
C. of ; do
D. of ; have