Dire qu'on est d'accord :

• Excellent idea ! Why not ?
• That's a very good idea !
• I agree with you.
• I think you are right.
• I share your point of view.
• That's also my opinion .

Dire qu'on est pas d'accord :

• This is completely ridiculous !
• It seems a shame !
• Oh no ! Are you crazy ?
• You can't say that !
• I don't agree / disagree with you.
• I think you are wrong.
• It is wrong to say that …
• I don't share your point of view
• I’m not convinced at all by what you’re saying …

 Pour donner son opinion :

• I think that ...
• As for me, ...
• As far as I'm concerned, ...
• In my opinion, …
• It seems to me that …
• I feel / believe that …

Pour dire qu'on ne sait pas trop quoi dire ...

• I don't know what to say...
• I have got no idea ...
• No comment !
• Well ... I have no opinion on that...

Pour avancer des arguments :

• You may be right, but ...
• I see your point, but ...
• For example, ...
• It's a fact that ...