---Is there anything wrong, Bob? You look sad.---Oh, nothing much.In fact, I ____ of my friends back home.
_____ is the population of your country?
Please say "Hi" to Bob ______ me.
After we walked ______ the forest, and ______ a river, we arrived at that small village.
We were about to leave the classroom _____ it began to rain.
Three students in ten will go and _____ to stay in the classroom.