为什么气焊时两块焊件的焊接接头要开坡口？
参考答案：
气焊时两块焊件的焊接接头开坡口，可使焊接过程中焊件充分焊透，确保接头焊接牢固。
---I’m fed up with studying.
---What nonsense! You’ve only got one year more to do. Then you’ll have your qualification and after that _____________
A．content is better than riches
B．it is not your cup of tea
C．the world is your oyster
D．well begun is half done
