求专业英文翻译高手！英文译成中文，不要翻译器翻译，高分献上，谢谢！

young students often struggle with abstract concepts in mathematics,causing primary teachers to continue to search for ways to help teach such concepts 小学生通常会纠结于抽象的数学概念，致使小学老师一直试图寻找传授这些概念 的教学方法。 .Principles and Standards for School Mathematics(NCTM,2