Play, often seen as________activity for kids, is still important in______development of teenagers.
---How long _______ each other before they ________ married ? -- -For about a year .
I really wonder ______ he has posted me many parcels _____ we worked together .
It is a rule in his family that ______ comes home earlier should cook the dinner for the family .
The duties of a policeman are _____ than ____ .
The black horse is _____ of the pair .