瓷粉的主要物质是
A.Al2O3
B.SiO
C.In2O3
D.K2O·Al2O3·H2O
E.Fe2O3
参考答案:D
—How do you your summer vacation?
—It's great. I love it.[ ]
A. like
B. know
C. think of
D. think
乙烯制冷压缩机开车前透平必须盘车24小时以上。