对中学生来说学习一些性常识是对的。
It's only right for middle school students to learn something about the facts of life.
太多的作业对中学生来说太不健康了。
Too much homework is much too unhealthier for middle school students.
这个型号的打字机对中学生来说，高效、耐用、经济、实惠。
This model of typewriter is efficient and durable, economical and practical for middle school students.
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