In life,there is something,though someone may tell you how to do,in your practice,you will meet some difficulty.Recently,l practised basketball shoting almost everyday,before this,l searched the lnternet to learn shooting key points.Happily,l think l master all of them,but when l really practise it,although l do as the key points,l find something difficult,however,not because the key points,but for you!Between theory and practice,there is something more important.To know it,you need ability of understanding.so some truth.only a few can really know,If you know how to do,why don't you do it by yourself?You must know,after doing that ,you will be clear!