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1·Objective: To evaluate the effeteness of argon laser in preventing the recurrence of pterygium.

目的：探讨低能量氩离子激光在防止翼状胬肉术后复发中的作用。

2·If the charge system is implemented, the highway become exclusive in consumption and the economical effeteness is depending on the specific conditions.

如果对使用公路实行收费制度，则在消费上具备了排他性，至于收费方式是否经济依具体情况而定。