Tony, you look puzzledHave you understood me ? —- I’m sorryI _____ another problem just now

ousin is said ________ anew computer program recently, but do you know when he will finish it

Where did you get to know her –It was on the farm __________ we worked.

John’s father went to Nanjing ________ten days ago.

After class, students ______ clean the chalk off the blackboard.