0. That______(science) began to study Russian in 1999.
1. Please mind your______(behave) in public.
2. The boss showed such______(patient) that he cut short my presentation.
3. The green light is on, and children can cross the road in______(safe).
4. This idiomatic______(express) seems out of style. today. We seldom use it.
5. Their lives were frequently______(threat) by earthquakes and volcanoes.
6. Though he is over 60, my grandfather always looks fresh and______(energy).
7. The young are on their way to make great______(contribute) to society.
8. I'm______(gratitude) to you for all the help you've given me.
9. The book written by this Nobel Prize winner is really worth______(read).