Students don't go to school _____ Saturday and Sunday.[ ]
A. in
B. on
C. during
D. at
答案:B
治疗血热夹瘀的出血证,宜选用()。
A.地榆
B.艾叶
C.仙鹤草
D.茜草
E.降香
常用的助焊剂为()型。
A.热固化
B.冷固化
C.红外光固化
D.紫外光固化