(1)如图:若ED,BC被AB所截,则∠1与∠2是同位角,
(2)若ED,BC被AF所截,则∠3与∠4是内错角,
(3)∠1 与∠3是AB和AF被ED所截构成的内错角,
(4)∠2与∠4是AB和AF被BC所截构成的同位角.
故答案为∠2;∠4;ED,内错;AB,AF,同位.
(1)如图:若ED,BC被AB所截,则∠1与∠2是同位角,
(2)若ED,BC被AF所截,则∠3与∠4是内错角,
(3)∠1 与∠3是AB和AF被ED所截构成的内错角,
(4)∠2与∠4是AB和AF被BC所截构成的同位角.
故答案为∠2;∠4;ED,内错;AB,AF,同位.