Brush your teeth at least （two） a day：in the morning and before bedtime．
康康在上音乐课的时候，Darren在爬山．
Darren was climbing a mountain while Kangkang ．
天太热了．我们不介意把窗户打开．
It's too hot．We don't mind ．
你们学校多久举行一次运动会？
does your school hold a sports meet？
上周，Jack从图书馆借了5本书．
Jack the library last week．
﹣Have you been to the Beijing Expo（北京世园会） in Yanqing？
﹣Yes， it's a of art， gardening， and high technology．（collect）