Originally, I wondered as well how Lois would have been able to knock Clark down since he is Superman. However, even though the show was a bit inconsistent with this, Clark can get knocked down when he is suprised. The boxer did it (sorry, don't remember episode titles much anymore). He got hit by a car once and knocked over. The point is, if he isn't expecting it, he's just as easy to topple over as anyone else.
His dense molecular structure might make it a bit harder, but Lois was reacting on instinct and probably had a bit of adrenaline to help her.
Very interesting story Wendy. Looking forward to more.
