水压试验完毕后进行降压时，其降压速度应控制在（）MPa；当压力降至0.2MPa时，开启疏水门、空气门。
参考答案：0.2～0.3
The second Sunday of May is ______ Mother's Day.
It's ______ special day for children to show their love for their mothers. [ ]
A. a; the
B. the; a
C. 不填; a
D. 不填; the
可控性玻璃屋顶采取玻璃屋顶和贮水屋顶、（）相结合的措施。
A.太阳能屋顶
B.普通屋顶
C.绿化屋顶
D.冷屋面
