周围神经系统中髓鞘形成细胞是()。
A、少突胶质细胞
B、施万细胞
C、卫星细胞
D、小胶质细胞
参考答案:B
— Did you see Tom at the party?
— No, he ______ by the time I got there. [ ]
A. left
B. was leaving
C. had left
D. has left
作物播种前晒种的作用是有利于()。
A.去除瘪子
B.去除沙子
C.去除杂种
D.杀菌