有复数，复数是by themself，例如：
1、Students could actively participate in experiment design， experiment discussion and lay out the experiment scheme， and fulfill the experiment by themself.在教学方法上注重突出学生的主体作用，学生主动参与实验设计、实验讨论、实验方案的确定，独立完成实验过程的教学形式。
2、Strongly requiring basic skill lets the students not have the chance to explore the interested math problems by themself and not gain the better feeling of it.对基本功的过度追求，使学生没有机会自主探索感兴趣的问题，学生无法获得对数学的良好感受。
