加热炉炉管结焦的原因有哪些?
参考答案:
炉管受热不均匀,火焰扑炉管,炉管局部过热;进料量波动,油温忽高忽低,或流量过低,油品停留时间过长;炉管中的介质易分解或含有杂质。
下图所示钱币出自我国古代哪个历史时期?
A.秦朝
B.汉朝
C.唐朝
D.宋朝
Tom is very _____ his new mobile phone and he always shows it to others. [ ]
A. proud of
B. good at
C. interested in
D. famous for