单项选择题 硅酸盐水泥掺活性混合材料时，最大掺量不得超过（）；掺非活性混合材料时，最大掺量不得超过（）。

单项选择题 听力原文：W: My room smells of cigarette smoke. I can't stand it. Could you change my room, please?M: Let me see... I'm sorry, but we don't have any more non-smoking rooms. We won't charge you for your room tonight.Q: what can you learn from the conversation?(19)A．The woman doesn't want to pay for the room.B．The woman likes smoking.C．The woman wants to have a non-smoking room.D．There's no more room in the hotel.

单项选择题 根据《房屋建筑与装饰工程工程量计算规范》的有关规定，天棚吊顶的工程量计算规则，下面说法错误的是（）。