French language Q&A Forum

In exercise "Fishing with my father C1". Could you please explain the use of devais in 

je ne devais pas avoir plus de dix ans. If it's; I mustn't have been... isn't that the passe composse ?

When ı had a look at the irregular adverbs forms I saw that the irregular form of "le plus mal" was "le pire"
isn't it incorrect? Because when I investigated it I saw that it must be "Le pis"

C'est lui qui danse le plus mal   He's the one who dances the worst. (I think this is correct)
C'est lui qui danse le pis   He's the one who dances the worst. (I think this is correct)

C'est lui qui danse le pire  He's the one who dances the worst. (I think this must be incorrect)

Am I wrong? 
please help

All the examples are with the verb ETRE.(TO BE). Is it correct to assume that this construct can work for ALL(??) 'copular' type verbs. I can't see it working with non 'copular type' verbs.

1)He looks great..and she does too == il a l'air bien et elle l'a l'air  aussi(not sure of this one)

2)The roses smell pleasant and the carnations smell pleasant too== les roses sentent agréables et les oeilets le sentent aussi(smells ok to me).

etc etc!!

3)what about a sentence like "she became angry then they became angry too== elle s'est mis en colere  ensuite ils le se sont mis (??)

Just asking 'for a friend' could you add a note in the lesson that the direct object pronoun occupies its usual place before the verb ...although it is acting like an adjective,