It's up to you. 的意思是“由你来决定，由你说了算！”

　　例句：

　　You can have any sweater you want . It’s up to you. The color’s up to you.

　　你想穿什么毛衣，你自己定，颜色由你来选。

　　I don’t know. It’s up to you.

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