题目内容
交流电循环变化一周所需的时间称为周期，用符号（）表示。
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Write a memo in about 50 words. You are Human Resources Manager. Your company is going to provide the staff with training in E-Commerce. There will be two course levels: intermediate level and advanced level. The training course will be given on Saturdays for five weeks. Write a memo to department managers: ·Informing them of the coming training course; ·Asking them to encourage the staff to participate; ·Asking them to help obtain the names of the interested staff.
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