砌筑沼气池的砂浆组成材料有哪几种？
参考答案：
砌筑沼气池的砂浆主要由水泥、砂和水组成。
Less than ten percent of the employees in their company are women. That is to say, women are in the______.
A．majority
B．activity
C．minority
D．probability
治疗流行性脑膜炎，下列药物中应首选
A．磺胺嘧啶
B．磺胺甲基异噁唑
C．甲氧苄氨嘧啶
D．磺胺醋酰
E．柳氮磺吡啶
