Qual è la differenza tra Let's have dinner our if you are not (=unless you are) too tired. e . I'll be quite glad if she doesn't come this evening. (o)
. I'll be quite glad unless she comes this evening. (x) ?Sentiti libero di rispondere con un esempio.

1) "Let's have dinner out if you're not too tired." It's ONLY IMPLIED that the speaker wants to have dinner with the listener.

2) "I'll be quite glad if she DOESN'T come this evening." The speaker DOESN'T want her to come, and if she does come, he won't like it. His emotions are very clear.

3) "I'll be quite glad unless she comes this evening." The speaker DOESN'T want her to come.

Difference between 2 and 3:
In 2, he clearly doesn't want her there. His emotions before she comes are positive (only slightly implied), and if she comes it's negative (very clear).

In 3, his emotions before she comes are positive (very clear), and if she comes, it's negative (only slightly implied).