I’m glad to receive__________ (你的电子邮件).
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I’m very sorry for I didn’t ______________ (早点回复你的邮件).
This e-mail is to___________ (告知你) that I’m thinking about studying in the U.S. next year.
I___________(将不胜感激) if you could give me your best quotations .
[多选题]-( )的受热面的烟气侧是以对流放热为主,所以称为对流受热面。
A. 对流式过热器
B. 锅筒
C. 省煤器
D. 空气预热器
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