肝小叶内不包括（）
A.肝板
B.中央静脉
C.肝血窦
D.胆小管
E.中央动脉
参考答案：E
It was in the factory _________ his friend worked _______ he picked up a lot of experience. [ ]
A. where, where
B. that, where
C. that, that
D. where, that
按焊条的用途分类，下列焊条中属于此分类方法的是（）。
A.堆焊焊条
B.碱性焊条
C.酸性焊条
