利用物质的物理变化获得低温,我们把这些物质称做()。
参考答案:制冷剂
— Mary divorced again last week.
— Why did she do a thing like that? It seems to make no _____. [ ]
A. difference
B. comment
C. sense
D. meaning
由于粒煤颗粒较大难燃烧,喷吹粒煤应具备的条件是什么?