1.They often went to school by bike when they were young
->They used.to go to school by bike when they were young.
2.She has taught her children to pay the piano for 4 years
->She started teaching her children to play piano 4 years ago.
3.It's a pity I can't cook as well as my mom
->I wish I could cook as well as my mom
CT:S1+ wish+ S2+ V(lùi thì).
used to + V: đã từng làm gì.
S+started+P2/Ving/+O+for/since...