1) Phrase a) Since I am not rich I didn’t buy that new Mercedes we saw yesterday. Unfortunately, I can’t even afford a used car. (la phrase (a) doit donner lieu à un mixed conditional) Pourrait-on aussi trouver une autre formule pour la deuxième partie de la phrase de sorte que l’étudiant soit oblige, dans la phrase (b) d’utiliser le modal « can’t + afford » ? par ex : Unfortunately, I’m not in a position to afford… (où qqch comme ça ?) I don't understand what you mean by a mixed conditional.
Phrase b) If… I were rich, I would buy that new Mercedes we saw yesterday. Unfortunately, I can't even afford a used car.
2) Phrase a) Come on, let's go to lunch. We haven't been out together for lunch in ages.
Phrase b) Come on, let's go to lunch. It… has been ages since we've been out together for lunch. (ces 2 phrases sont-elles complètement compatibles ?) Yes... based on the previous sentence.
3) Phrase a) We haven't been to this restaurant for a long time - look what's happened to the prices.
Phrase b) It... has been ages since we've been to this restaurant - look what's happened to the prices. OK
4) Phrase a) Mom, you said we could go to the park a long time ago. When are we leaving?
Phrase b) Mom, it... has been ages (or, it's been a long time) since you said we could go to the park. When are we leaving? OK
5) Phrase a) All employees must / should be dressed in their proper uniforms // must / should be properly attired in their uniforms before 6.30 am.
Phrase b) It is very important that... all employees BE DRESSED in their proper uniforms before 6.30 am. OK
6) Phrase a) Holden Caulfied's parents weren't careful about his upbringing; and you can see the result.
Phrase b) If... his parents had been more careful in his upbringing, Holden Caulfield would have been quite different. OK