用于焊接过程中，预热区，焊接区，冷却区氮气保护，杜绝焊点或铜箔高温下氧化，提高焊点质量是设备里抽风系统的功能。
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What is one country in the Middle East trying to do?
A. Create a new government.
B. Make its citizens happier.
C. Make the world people happy.
D. Create a new office in the government.
What do people complain about the government?
A. The government doesn’t do anything to make people happy.
B. The government doesn’t care whether people are happy or not.
C. The government hasn’t created an office to study people’s happiness.
D. The government hasn’t solved many problems that make people unhappy.
下列牌号钢筋中,属于热轧带肋钢筋的是( )。
A. HPB300
B. HRB600
CRB550
D. Q235B
碳素结构钢的牌号由代表____、____、____、____等四个部分按顺序组成。
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