Though he started late,Mr.Guo played the piano as well as,if______,Miss Liu.

___________ to give up drinking, my daddy threw away all his ________ bottles of wine last night.

In that school, English is compulsory for all students, but French and Russian are _________.

It is not socially          for parents to leave children unattended at that age. 

Overpopulation is a terrible threat to the human race.Yet it is probably ____ a threat to the human race than environmental destruction.