What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If Charles makes tea, then Elisabeth is fast. If Elisabeth were fast, then Barbara is taking a plane. If it is sunny, then Barbara is not taking a plane. If William plays squash, then Elisabeth is fast. William is playing squash or Charles is making tea.
If Charles makes tea, then Barbara is taking a plane. If William plays squash, then Barbara is taking a plane. Elisabeth is fast.