The laser energy removes the brown pigment, or melanin, from the top layer of the iris, and the blue eye colour emerges over the following two to three weeks.

激光能去除眼球虹膜最外层的棕色素或黑色素，而蓝眼珠会在两到三周之后显现。

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B Instead of Chinese summer vacation and winter vacation, Americans have two or three weeks off from work specifically for vacations.

取而代之中国的寒暑假，美国人的工作假期也有两、三个星期。

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We have to give him time now to recover from that intense preparation but, in two or three weeks, he will have done that and might play as well.

我们现在必须给他时间从剧烈的身体准备中恢复过来，但在两到三周内，他将会恢复体力，并且又将上阵比赛。

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In a preliminary study he conducted in 22 post-stroke patients using error-type training, he found 15 consecutive days of intense treatment yielded as much improvement as what patients got from intense conventional treadmill training two to three times a week in 10 or more weeks.

WSJ: Split-Belt Treadmill Therapy for Stroke Patients