I presume you offer that as a counterexample. If so, you should be able to make a statement - write out an actual sentence or paragraph - that is both true and untrue in the same sense at the same time. Let's try a few:
- The cat is dead. If the cat is dead, it is not alive. Only one of those can be true at a time.
- The cat is alive. Same answer.
- The cat is both dead and alive. If the cat is both dead and alive, it is not just one or neither. But notice that these words are being used differently than earlier. This "live" cat won't meow.
- The cat is neither dead nor alive. Same answer.
You can say that in a sense, the cat is both dead and alive and neither dead nor alive, but those are different senses of what dead (and alive) mean - potentially dead versus actually dead, in a superimposed state or a collapsed probability wave state.
Consider
@ChristineM 's picture of the plates. There's a sense in which the plates are both broken and intact, but in another sense, they are only intact, soon to be broken. Potentially broken is not actually broken.