apply for ;apply to ;apply oneself to 的区别用法是什么?请解释并举例.

apply for ;提出申请 He is applying for a job.他在申请一份工作.apply to :把...应用于...We should apply what we have learnt to our practical work.我们应该把我们所学的应用于我们的实际工作中.apply oneself to 专心从事...埋头于...Students should apply themselves to their study.学生们应该专心学习.