Voi khoang cach' 30 m tro len minh lai sut' = O ;)) chinh huong' giu~ chat tien' + R2 , neu' sut chan phai an' them nut' sang trai'( va ngc lai. ) lam` cho bong' di cong , ti le thanh cong kha' cao ;))
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cach sut' nay khoang cach tu` 30 - 35 m con` xa hon thi chua biet...