脊髓表面的纵行沟裂有（）。
A.3条
B.4条
C.5条
D.6条
E.8条
参考答案：D
铅酸电池为什么要用三段式充电方法充电？
Our headmaster asked us _____ a report on how to protect wild animals. [ ]
A. write
B. writing
C. to write
D. wrote
