. Only when Tom fully recovered ______ back to work.
In recent years, with the help of our teacher, I have made_____ rapid progress in ____math.
Several weeks had gone by _______ we realized the painting was missing.
_______ we realized the painting was missing.
Although _______ of danger, tourists can't help taking photos near the cliff.
_______
Many websites have been _______ to help people study foreign languages.
---Can I join the club, Dad?---You can when you ______ a bit old.