Person of verb in a compound subject

Question

This came up in the examples of the use of stress pronouns: Ma femme et toi êtes meilleures amies.  But why is it 'êtes' and not 'sont'?

Anne Davies · Accepted Answer

Jane H, look again at the section headed "Here are more examples" - the sentence is correct but feels unnatural to an English speaker because English (edited) plural verb forms for we, you and they are all the same. In French, Ma femme et toi takes the second person plural form of the verb, Toi et moi or Jean et moi the first person plural and Lui et Sarah or Hugo et eux the third person plural.
I find it easier to translate by mentally adding in a subject pronoun : Jean and I (we) went to the cinema, He and Sarah (they) are going to come etc
 
It’s always worth browsing the Q&A section under a lesson, too

Céline Pickard · Answer

Bonjour Jane,
Anne's explanation (and trick) are great!
"Ma femme et toi" means "my wife and you". As soon as the stress pronoun "toi" (= you) is part of a compound subject, the whole thing can be replaced by the subject pronoun "vous" meaning that the verb will be conjugated with the second person plural form.
Remember:

[name] + moi -> can be replaced by the subject pronoun "nous" (= we)
[name] + toi -> can be replaced by the subject pronoun "vous" (= you)
[name] + nous -> can be replaced by the subject pronoun "nous" (= we)
[name] + lui/elle/elles/eux -> can be replaced by the subject pronoun "ils/elles" (= they)

I hope this is helpful.
Bonne journée !