椅子在桌子的前面\The chair is at the front of the desk./ The chair is before the desk.
他昨天在弹钢琴 He was playing the piano yesterday.
我现在在扫地\I am cleaning the floor now.
他明天要去加拿大\He will go to Canada tomorrow.
球在床下面\ The ball is under the bed.
他们昨天在跑步\They were running yesterday.
纸是由木头制造\ Paper is made of wood.
我们下星期要去参观博物馆\ We will (go to) visit the museum next week.
他们现在在农田工作\ They are working in the farm now.
他在看电视\ He is watching TV.
我们现在在上课\ We are having class now.