My nephew often flied a kite in this field when he was a child.
A.My nephew is used to fly a kite in this field when he was a child.
B.My nephew used to fly a kite in this field when he was a child.
C.My nephew was used to fly a kite in this field when he was a child.
D.My nephew used for flying a kite in this field when he was a child.