"我已经订购了" 的英文表达是 "I have already placed an order."。
这句话的来源是英语中的常见表达方式，用来表示在过去的时间里已经完成了订购某物的动作。
下面是一些例句和中文翻译：
"I have already placed an order for the new phone." (我已经订购了新手机。)
"I called the restaurant and placed an order for pick-up." (我打电话给餐馆，订购了外卖。)
"I have already placed an order for the tickets, so we just need to pick them up at the box office." (我已经订购了票，所以我们只需要在售票处取票即可。)