过热器出口安全阀有几个?各是什么形式的?
参考答案:
出口安全阀有3个,1个电磁式和2个弹簧式。
Daniel is good at DIY. He can ________ different kinds of things with his hands. [ ]
A. write
B. play
C. watch
D. make
连续缺2个刮板的刮板输送机为不完好的设备。