The headmaster was dismissed three months ago.The post is too important to leave __________ any longer,especially before the college entrance examination.
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.
The beef is too expensive. I won’t buy it _____.