Is this sentence the right way round? Should the subject not come before the verb? I.e cand copii tai au inotat? (Sorry can't type the diacritics on the computer yet)
In this case the verb is before the subject
Should it really be written with three "i" ?
Your children = "copiii tai" or "copii tai" ?
To use the possesive you have to literally say The your children. and Copiii is the articulated plural meaning THE children whereas copii just means children.
Why "when have your children swum" is wrong?
I think "swum" may be a bridge too far in understanding for Duo.