问题
单项选择题
为保证焊缝质量，使氧化物还原，在焊条药皮中要加入一些( )。
A．还原剂
B．催化剂
C．氧化剂
D．活化剂
答案
参考答案：A
解析：药皮除具有机械保护作用外，还要加入一些还原剂，使电弧燃烧中产生的氧化物还原，以保证焊缝质量。
搜题请搜索小程序“爱下问搜题”
为保证焊缝质量，使氧化物还原，在焊条药皮中要加入一些( )。
A．还原剂
B．催化剂
C．氧化剂
D．活化剂
参考答案：A
解析：药皮除具有机械保护作用外，还要加入一些还原剂，使电弧燃烧中产生的氧化物还原，以保证焊缝质量。
It was a cold winter morning. Half asleep at the train station, I stared into the distance, 36 for the train to take me to my 37 in Boston. The word was quiet. The very few people on the street kept to themselves, 38 their steaming cups of coffee. Reaching into my pocket as the 39 was approaching, my numb hand searched for the $ 20 bill to pay my fare. The pocket was 40 ! I searched through my bag and then I felt 41 . Unless the money dropped from the sky, I’d be 42 there. “What’s the matter?” A short, elderly man stood before me. “Oh, nothing…. Well, I 43 my money and now I can’t pay for the ticket. I’m going to 44 my match class, and the train is leaving.” “Here, use this.” The man held a $ 20 bill. I looked up, 45 . People just didn’t do that anymore. Everyone worried about their own 46 , rarely stopping to think about others, especially teenage strangers. “Thank you, but no, I can’t.” “ 47 it – go!” The man pushed me 48 the train. I bought a round – trip ticket, and he refused the change I 49 to give him back. I did not know what to say – a million thoughts raced through my mind, yet I stood 50 . For the train ride I was silent. I began to see the world through 51 eyes. That man made a difference with such a simple 52 . A week later I was at the train station again, with an extra $ 20 53 I saw the man. And there he was. “excuse me, sir, I believe I owe you this.” I 54 the money into his hand. Failing to refuse, he said, “Just remember to do the same for someone in your shoes someday.” I smiled, content. The elderly man is my hero. For many, heroes are famous, but my hero is a 55 stranger who taught me a lesson in life. I will never forget his kindness.
|