In the year 2010,the world’s population was over 7 billion_____________（总共）
Let’s ______________a time to talk about the art competition.（约定）
If you don’t go to the mountain tomorrow, _______________.（我也不去）
I’m nineteen years old ,and next Sunday is my ______________birthday.（第二十）
He didn’t come back from work____________midnight.（直到）
If you want to be a _____________visitor, it is important to ask for help_____________.（礼貌）
