A:弯向光源 弯向孔
B:弯向光源 弯向光源
C:弯向孔 弯向孔
D:弯向孔 弯向光源
—Where are you from?
—I'm from the UK.
解:∵∠A=∠F
∴AC∥____(内错角相等,两直线平行)
∴∠1 =∠D(____)
∵∠C =∠D(已知)
∴∠1=____(等量代换)
∴BD∥____(____)