— I hear the famous singer Xu Song may come to Ningbo next month.

— Really? _______ he comes, my younger sister will be very excited.

A．If

B．Until

C．Unless

D．Before

下列哪一项表现是去大脑动物所没有的（）。

A.脊髓休克

B.伸肌紧张亢进

C.迷路紧张反射

D.颈紧张反射

E.牵张反射