用所给词的适当形式填空
①To make a sandwich, we need two ____ (slice) of bread, some vegetables and some meat.
② It rained hard yesterday, but ____ (luck) we brought our raincoats and didn't get wet.
③Ted told us an unusual story ____ (call) Mystery steps.
④ Cindy had fun ____ (make) flashcards with her cousin.
⑤ How old was Laura when she became a ____ (skate) champion?
