某焊机的额定焊接电流IN是300A，额定负载持续率DYN是60％，求在工作周期内焊机连续负载的时间t？
参考答案：
该焊机连续负载时间为3min。
吗啡戒断症状产生主要是由于
A．去甲肾上腺素能神经元活性增强
B．胆碱能神经元活性增强
C．多巴胺能神经元活性增强
D．5-羟色胺能神经元活性增强
E．脑啡肽能神经元活性增强
The table above shows the number of tickets sold during each of the first 4 weeks after a movie was released. The producer of the movie received 10 percent of the revenue from every ticket sold with a guaranteed minimum of $200,000 per week for the first 4 weeks. If tickets sold for $4 each, how much did the producer receive for the first 4 weeks ？（）
A．$800,000
B．$900,000
C．$1,000,000
D．$1,200,000
E．$1,300,000 250,000×4×10%=100,000
