1. What happens to A when B is changed?
2. What happens to A when B will be changed? (this one seems to be wrong, right?)
3. What happens to A when B gets changed?
You need the first one. The last one is possible, but it's in a lower register. Personally, I would not use it.
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You need the first one.
The last one is possible, but it's in a lower register. Personally, I would not use it.
I don't recommend the middle one. No.
CJ