Doublefeed systems work well if the grid voltage and frequency is very stable.
当网格电压和频率很稳定时，双馈系统工作的很好。
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The World Health Organisation has predicted that meat consumption will double by 2050, and the increasing cost of animal feed is likely to rapidly inflate the price of meat before then.
The most complicated thing in the whole design is the feed system, which includes several parts to avoid double and even triple feed with the extremely long projectiles.