Miss Jie asked a math problem: S is a point outside the plane of rectangular ABCD. .....
Methods 1: Take the Q point on AD, so that Se: ED = BF: FC = AQ: QD. Prove the aircraft EFQ// SAB and get the aircraft EF// SAB.
Method 2: Take a little Q from SA to make SE: ED = BF: FC = SQ: QA. The quadrilateral EFQB is a parallelogram, so the EF// plane SAB is proved by EF//QB.