为了确保锅炉安全经济运行，必须配置安全阀、水位计、膨胀指示器及吹灰器等锅炉附件。
参考答案：对
若x2+mx＋9是完全平方式，则m的值是 .
Where is my ball? I remember I put it here yesterday.
--You it in the wrong place.
A．must put
B．might put
C．should have put
D．might have put
