下列关于神经纤维(单根)的描述中,哪一项是错误的
A.电刺激可以使其兴奋B.阈刺激可以引起动作电位C.动作电位是“全或无”的D.动作电位传导时幅度可逐渐减小
参考答案:D
In my opinion, life in the twenty-first century is much easier than ____.
A.what used to be
B.that it used to be
C.it used to be
D.what it used to be
要使39口750≈40万,口里有( )种填法.
A.1
B.4
C.6
D.5