防止电极硬断的措施？
参考答案：
⑴、缩短热停时间，减少热停次数
⑵、停炉前电极不要太长
⑶、注意观察维护电极
⑷、停炉送电后，升负荷不要太快
China has launched another man－made satellite，________ is announced in today's newspaper.
A．that
B．which
C．who
D．what
I think _______ necessary for you _______ breakfast.
A．this; have
B．that; to have
C．it’s; to have
D．it’s; have
