She a student ten years ago, but she a teacher now.
A. is; was
B. was; is
C. was; was
答案:B
智能障碍的主要症状包括_____________、______________、_____________、______________。
超微粉碎技术不包括以下哪项内容:()。
A.对原料的超微粉碎
B.提高原料稳定性
C.高精度分级
D.表面活性改变