We can use "hello" to greet people in an informal situation.
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In social situations, a woman would be introduced to a man first.
A. 对
B. 错
It is impolite to give your name without saying "hello: in an introduction.
A. 对
B. 错
传统热连轧、CSP、ESP和铸轧薄带钢生产各有哪些优点