多项选择题

纯铜焊接过程产生的气孔是（）气孔。

A．H₂
B．N₂
C．CO
D．CO₂
E．NO

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【简答题】You planned to go to the National Library with your friend tomorrow. But now you have an important job interview. Write an email to him/her to 1)make an apology, 2)ask for advice for the interview. Do not sign your name. Use 'Li Ming' instead. Do not need to write the address. You should write about 100 words neatly on the ANSWER SHEET.

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