The first utterance was shown to be heavily constrained : it must introduce a problematic issue. Are there such restrictions on what can be answered by interlocutors ? A very simple way to react is simply to acknowledge the problematic side of the issue, adding it explicitly to the common ground [Clark & Schaeffer 1989]. Here is an example :
[ex_christmas-tree]
context: three weeks after Christmas, the Christmas tree is still green.
A1- Mais c'est toujours le sapin? C'est formidable, a!
B1- Mais oui! Il n'est pas encore sec!
A2- Et sans racines?
B2- Sans racines. Il perd même pas ses... On a déjà coupé toutes les branches du bas.
A3- C'est curieux qu'il ne perde pas ses...
B3- Ben oui, je ne comprends pas.
A4- Il est en plastique !
A1- Is that still the same Christmas tree? This is unbelievable !
B1- Oh yes! It hasn't dried up yet!
A2- And without its roots?
B2- Without its roots. It doesn't even lose its... We already cut the lower branches.
A3- It's strange that it does not lose its...
B3- Yes it is. I can't understand why.
A4- It is made of plastic !
We can observe how both interlocutors emphasize the paradoxical side of the situation, from A1 to B3. We have the same phenomenon with improbable or (un)desirable topics. We will be more concerned here with other kinds of replies, which have a definite effect on the problematic issue.