预制板块屋面防水保护层块体间要预留______mm缝隙，待1～2d后再用1:2水泥砂浆勾成凹缝。
A．10
B．15
C．20
D．25
参考答案：A
根据句意及汉语提示填空
1. —What's this?
—It's an ______ (橘子).
2. Jane and Jim are my good ______ (朋友).
3. —Are ______ (这些)cars?
—Yes, they are.
4. They are five ______ (蛋糕).
5. —What's that in ______ (英语)?
—It's a ruler.
立装搭接的圆筒环缝时，用什么定位？最后用什么夹紧？
